The Empire Strikes Back

In the asteroid scene, one of the asteroids is actually a shoe. The rumor is that George Lucas asked the SFX people to redo the scene so many times that they got annoyed and one of them threw in their shoe.
Another of the asteroids is actually a potato. It appears just as the Millennium Falcon first enters the field. Two asteroids travel from the top left to the bottom right corner of the screen. Just after the second asteroid leaves the screen a third one appears in the top left corner. This is the potato.
Lighting for SFX was so strong that several models melted.

The AT-ATs were inspired by the walking machines in H.G. Wells's "War of the Worlds" and their appearance was based on gantry cranes which are used in most shipping ports in the USA. Walking patterns of elephants were studied to make the movements seem as realistic as possible.
Further scenes with the Wampa were shot, and later cut. R2-D2 encountered one within the Rebel base, where it was killed by troopers. Later, the beasts were lured into a prison within the complex. In the completed film, a medical droid is seen examining the wounds of a tauntaun killed by a Wampa, and Princess Leia mentions the "creatures" while discussing the Imperial probe droid. A scene filmed but cut had Han, Leia and C-3PO running through a corridor. Han went to take a short-cut through a door with a sign on it, but Leia warned him "that's where those creatures are kept". They run off, but not before C-3PO rips off the sign, hoping that the stormtroopers will enter the room. They did.
A few seconds of C-3PO ripping off the warning sign from the cut "wampa pen" scene can be seen in the theatrical trailer on the DVD
The blasters used by the stormtroopers were constructed from Sterling L2A3 Mk 4 submachine guns.
Originaly, the scene where Han rescues Luke on Hoth was to have been filmed at Elstree studios, and only Mark Hamill was needed on location in Norway. But when a glacier made it impossible to film anywhere but near the hotel, Harrison Ford was summoned to Finse, anyway. Unable to travel by train, he arrived in the engine compartment of a snow clearance vehicle.
Carrie Fisher traveled to the filming location of Finse, Norway, even though she was not scheduled to take part in any outdoor scenes.
The Dagobah set needed to be elevated to give Frank Oz and three other puppeteers room to control the Yoda puppet from below. For proper interaction, Mark Hamill was given an earpiece so he could hear Frank Oz doing Yoda's voice. Mark Hamill reportedly had a hard time concentrating on his dialogue, since his earpiece occasionally picked up a radio frequency playing the Rolling Stones.
Frank Oz (Yoda) was beneath the set floor doing Yoda's voice. On numerous occasions, George Lucas would give a direction to Yoda by mistake and Frank Oz would have to remind him who to talk to.
When shooting on location in Norway, a fierce snow storm hit the hotel where cast and crew were staying. This would have normally halted filming, but director Irvin Kershner thought these weather conditions were an excellent opportunity to film the scene where Luke wanders through the snow after escaping the Wampa cave. He did this by sending Mark Hamill outside into the cold, while he and the cameraman stayed and filmed inside the hotel's front hall.
Original start date of shooting at Elstree was slated to start in March 1979 but was delayed for three months because at that time, set 3 of the studio which was used for The Shining was burned down and had to be rebuilt at a higher scale
Production was stopped at one point following the death of production designer John Barry. Norman Reynolds took over Barry's duties.
About twenty minutes into the movie there is a shot in the Hoth base control room in which we hear Han's voice over radio describing what's left of the probe droid. One of the background sound effects in this shot was taken from the Canadian shortwave time signal station CHU, which can be heard at 3330 and 7335 MHz.
Director Irvin Kershner provided the voice of Darth Vader himself in the temporary mix of the film, before James Earl Jones recorded the final version.
For the 2004 DVDs, the scene with Darth Vader and the Emperor were redone replacing Clive Revill with Ian McDiarmid who played the Emperor in the rest of the series. The dialogue was re-recorded with Ian McDiarmid and James Earl Jones. Some additional dialogue was added.
The scene in the Cloud City apartment where Han Solo enters to tell Princess Leia that the repairs on the Millennium Falcon are almost complete played out differently in the finished film than it did in the original script. There, Han Solo (Harrison Ford) is lounging around in the apartment when Princess Leia (Carrie Fisher) enters, having changed from the white combat clothes she wore on Hoth to the brown dress and having her hair done up differently. In surprised reaction to how she's dressed, Solo attempts to flatter her ("You look beautiful. You should wear girls clothes all the time.") and Leia teases him by mentioning Luke; the scene ended with them sharing a kiss. The film was originally shot this way, but director Irvin Kershner felt it wasn't coming out right, so he re-shot it to appear as it does in the finished film. Excerpts of how the scene was originally filmed can now be seen on the special edition DVD.
When Han Solo is about to be frozen, Princess Leia says, "I love you." In the original script, Han Solo was supposed to say, "Just remember that, Leia, because I'll be back," but at the time of filming, Harrison Ford wasn't entirely certain he did want to come back for a third film. There is a recurring legend that his line, "I know", was ad-libbed; however Alan Arnold's book "Once Upon A Galaxy: A Journal of the Making of The Empire Strikes Back" includes a transcription of the discussion between Ford and Kershner in which Ford suggested the line.
In the DVD commentary, Carrie Fisher relates that during some of the London filming, she stayed a house rented from Eric Idle. Idle and the Pythons were filming Life of Brian (1979) at the time. One evening, Idle had a small party, including Harrison Ford and the Rolling Stones, and served a potent liquor (which the Pythons had been distributing to extras on their film, to help boost morale) that he referred to as "Tunisian Table Cleaner". They stayed up most of the night drinking and having fun. The first scenes shot the next day were the arrival at Cloud City, which she says helps explain why she and Ford were so happy in those scenes. Idle is said to be pleased that he had a small hand in how the finished film turned out.
In the famous scene right when Han is frozen, he replies "I know" to her "I love you". Originally, the scene was shot with Han replying "I love you, too", however, Harrison Ford didn't think that it fit Han's personality. George Lucas agrees, and Ford ad-libbed his now famous line.
Several crates of simulated snow as seen on the Hoth Hangar set were taken along to Finse, Norway, just in case there was not enough real snow lying about.
The entire Millenium Falcon was built live size for the first and only time for this installment (only half of the spacecraft was constructed for Star Wars (1977) and just part of it was used for the deleted sandstorm scene in Star Wars: Episode VI - Return of the Jedi (1983)). It measured 65 feet in diameter and 16 feet in hight with a mandible giving it an overall length of 80 feet. The Falcon's weight was 23 tons.
The Millenium Falcon was constructed in a hangar at Pembroke Docks where great flying boats were made in the 1930s. It was brought to Elstree studios, London in sixteen interlocking sections by a convoy of trucks. After reassembly, the Falcon was floated into position on the then brand new Star Wars stage by means of compressed air pads similar to those used on hovercraft.
Eight Artoo Detoos were used in the making of Star Wars: Episode V - The Empire Strikes Back (1980). Kenny Baker used two that were lighter and more comfortable than the ones from Star Wars (1977). Three were dummy versions which could be damaged and another three were remote controlled.
A total of 16 sets of Luke's combat outfit (aka "Bespin fatigues") were made.
Producer Gary Kurtz's wife Meredith organized a picnic on the Dagobah set for the wrap party on Friday, August 31 1979.
During principal photography it remained unclear if Sir Alec Guinness would return as Obi Wan Kenobi. Guinness was suffering from an eye infection at the time and was still a bit upset about the last minute decision of his character being killed off in Star Wars (1977). He finally did agree and worked one day on the film: Wednesday September 5 1979
In order to avoid sharing creative rights, George Lucas decided to avoid using a major studio to finance this film. Instead, he bankrolled the $33 million production himself, using a combination of his profits from Star Wars (1977) and a bank loan. Although the move was risky, it paid off several times over. Lucas then showed gratitude far beyond the Hollywood norm, by sharing the profits with his employees (nearly $5 million in bonuses).
To preserve the dramatic opening of the Star Wars movies, George Lucas insisted on moving all the credits to the end of the film. However, although the Writers' Guild and Directors' Guild had begrudgingly allowed this on Star Wars (1977) (because that film wasn't expected to be very successful), they resented the trend being continued on this film. First they tried to pull Empire from release, but were unsuccessful. They then fined Lucas heavily, and tried to fine Irvin Kershner, but Lucas paid all the fines himself (nearly $250,000). Lucas then bitterly dropped his membership in the Writers' Guild, Directors' Guild, and the Motion Picture Association of America, a move that has hindered his hiring choices on later films (see also Star Wars: Episode VI - Return of the Jedi (1983) and Star Wars: Episode III - Revenge of the Sith (2005)).
The carbon freezing chamber is the only time in the original trilogy that Darth Vader and C3PO are in the same scene together.
A total of 64 sets were constructed for the movie.
Irvin Kershner's involvement in the movie lasted a total of two years and nine months from start to finish.
The sound of Darth Vader's shuttle door opening is reportedly a recording of a whole block of Alcatraz cell doors slamming shut.
The scene where Solo was hit by the toolbox as well as hitting the control panels were improvised on the set. At first, the crew were afraid of shooting it, but Irvin Kershner finally persuaded them to do so, saying "Come on, that's fun. Let's do it!"
The two other scenes, which are the swamps of Dagobah; and the asteroid's creature (which has the Millenium Falcon) was done on the same sound stage used for the interior backgrounds of the Echo base in Hoth
The scenes where R2-D2 is submerged in the mud pool were shot in George Lucas' unfinished swimming pool. Most of the crew were hidden under the water and the entire sequence was shot by George Lucas himself.
On Hoth, General Rieekan says, "Send Rogues 10 and 11 to sector 38," a veiled reference to THX 1138 (1971).
Luke cuts off the Wampa's arm. C-3PO loses an arm when blasted by the Stormtroopers. Darth Vader cuts off Luke's hand. See also Star Wars (1977) and Star Wars: Episode VI - Return of the Jedi (1983).
More scenes of the AT-ST Imperial "chicken walkers" were filmed, but George Lucas decided that the larger AT-ATs were more menacing and impressive. He later realized that the AT-STs would work better in close quarters, which led to using them extensively in the forest battle in Star Wars: Episode VI - Return of the Jedi (1983).
Billy Dee Williams had previously auditioned for Han in Star Wars (1977).
The incident where R2-D2 accidentally electrocutes himself by mistaking a power outlet for a computer terminal was taken from the novelization for Star Wars (1977).
For the Special Edition, Vader's "Bring my shuttle" line has been replaced with, "Alert my Star Destroyer to prepare for my arrival." Sound designer Ben Burtt has confirmed that this is actually a line performed by James Earl Jones that was recorded for use in Star Wars (1977), but never used.
The following characters "have a bad feeling about this": Leia. See also: Star Wars (1977) and Star Wars: Episode VI - Return of the Jedi (1983).
Jeremy Bulloch, who plays Boba Fett, is producer Robert Watts's half-brother.
Denis Lawson plays Wedge Antilles. Wedge was not originally scripted to appear in this film, but intense fan interest prompted George Lucas to include him. See also Star Wars: Episode VI - Return of the Jedi (1983).
Leigh Brackett succumbed to cancer shortly after completing her first draft of the script of the film.
The voiceover line "The first transport is away" during the Rebel evacuation is delivered by Mark Hamill.
Mark Hamill's wife gave birth to their first son (Nathan Hamill) early one morning, and Mark went straight from the hospital to shooting. This was the day they filmed the shots of Luke hanging by the weather vane below Cloud City, on Bespin.
After an extra fell sick, Jeremy Bulloch (Boba Fett) was called in as a replacement to the Imperial Guard who escorts Princess Leia and pulls her into the elevator after she screams "Luke! It's a trap!". He's the same Imperial Guard who is captured by Lando Calrissian's men.
In the original script when Lando is about to lead Han, Leia, and Chewie into the trap set by Darth Vader, Lando offers his arm to Leia, as a gesture to lead her down the hallway and she accepts it. Harrison Ford ad-libbed Han coming up behind Leia and offering his arm to her at the exact same moment to imply that Han was jealous.
Carrie Fisher stood on a box for many of her scenes with Harrison Ford in order to make up for the height difference and have her appear in the frame with him. Carrie Fisher is about a foot shorter than Harrison Ford.
Luke is upside-down at the beginning (Wampa cave), in the middle (training on Dagobah), and at the end (below Cloud City). He uses the Force each time.
Having Han Solo frozen in carbonite was (at least in part) due to the fact that they were not sure that Harrison Ford would return for a third film. When the original Star Wars (1977) was made Carrie Fisher and Mark Hamill were signed for a three picture deal, but Harrison Ford refused.
The shots where Luke uses his Jedi powers to retrieve his lightsaber from a distance were achieved by having Mark Hamill throw the lightsaber away and then running the film in reverse.
Darth Vader's costume was more detailed in this film, including the flashing red lights on his chest box. A new Millennium Falcon (32-inches long) was built for this film and has two additional landing gear boxes on its underside. As a result, the original Star Wars (1977) model (5-foot long) was modified and given the extra landing gear bays and was used for all FX scenes of the Falcon in a landed position.
The concept design for Cloud City was originally created for Star Wars (1977) (as a floating Imperial prison), but was never used. The design was recycled for use in this film.
The lightsaber fight scenes set in the carbon freezing chamber tend to focus on Luke. This is because during many of the shots, Bob Anderson (Vader's fight double) was not wearing the Darth Vader helmet, as it made it difficult for him to breathe.
Mark Hamill had to bang his head 16 times on the ceiling of Yoda's hut before the director was satisfied.
During the filming of the Battle of Hoth, the Echo Base troops were actually Norwegian mountain-rescue skiers. In exchange for participation in the film, Lucasfilm made a donation to the Norwegian Red Cross
George Lucas was so impressed by Frank Oz's performance as Yoda that he spent thousands of dollars on an advertising campaign to try and get him an Oscar nomination for Best Supporting Actor.
Han Solo is the only non-Jedi/Sith in the entire trilogy to ever use a lightsaber when he cuts open the tauntaun's belly.
For the Dagobah scenes, Mark Hamill was the only one listed on the callsheets as an actor. Everyone else was listed as crew.
George Lucas decided that a battle on an ice planet was necessary because he felt that it was easy to "cheat" in space, because the background was black and you could hide errors easily. With a white background, the effects crews would have to work much harder, and the effects would be much more impressive.
The book "Star Wars: The Annotated Screenplays" reveals that, when the script for this movie was first written, the idea of it being "Episode V" of a 6 (or 9) part serial had not yet been established, and it was at one point called Episode II.
The AT-AT Imperial walkers were all animated through classic stop-motion techniques, except for the scenes where they fall, for example the walker which is "tripped up" by cables and falls on its face, or the one that Luke throws a grenade into, which falls on its side. These were filmed in real-time with precision-timed mini-pyrotechnic charges.
Most of the rebel ground troops in the Hoth battle were Norwegian extras. Because they didn't speak any English, Irvin Kershner had to "act out" what he wanted them to do, by pointing in the direction of the "enemy" (which wasn't visible during shooting) and demonstrating the recoil motion he wanted for the blaster rifles.
With the exception of being sucked out of a Cloud City window, Mark Hamill did all of his own stunts.
Most of the extras in the snowy battle scenes on the ice planet Hoth (shot at Finse, Norway) were Norwegians. One of the extras - Tom Egeland - would later become the chief news editor for one of Norway's largest TV networks, as well as a critically acclaimed mystery writer, one of the others - Arve Juritzen - would become one of Norway's best known TV-personalities (hosting "Who Wants to Be a Millionaire", "Big Brother", etc).
Yaphet Kotto was offered the role of Lando Calrissian, but turned it down because he believed he would be killed off and it would be difficult for him to find work after that.
Producer 'Gary Kurtz' came up with the title for the movie.
Producer 'Gary Kurtz' directed the scene in which Luke flees the Wampa ice cave. Kurtz took over John Barry's second unit duties after he suddenly died on the set until his replacement Harley Cokeliss arrived.
Temuera Morrison who played Jango Fett in Star Wars: Episode II - Attack of the Clones (2002) re-dubbed Boba Fett's lines for the 2004 DVD.
As Yoda and Obi-Wan urge Luke to stay on Dagobah to finish his training, Luke pulls a snake from his spaceship. Irvin Kershner assured Mark Hamill that the snake was harmless, though it did bite him during one take.
George Lucas's campaign to have Frank Oz nominated for a Best Supporting Actor Academy Award was ultimately rejected because it was felt that a puppeteer wasn't an actor.
The only Star Wars film that does not take place on the desert planet Tatooine (although it is mentioned by name at the end of the film).
One of the first ideas for Lando Calrissian was to have him as a clone who survived the Clone Wars who leads legions of clones on a planet they settled on. Another idea had Lando as the descendant of survivors of the Clone Wars, born into a family who reproduced solely by cloning. Originally, his name was "Lando Kadar".
One of the bounty hunters that Darth Vader hires to find Han Solo, IG-88, can be seen in the Cloud City. IG-88 is a droid, and his dead body is sitting next to a furnace in the room where C-3PO is dismantled.
Milton Johns is dubbed
WILHELM SCREAM: Heard twice in the film. Once during the battle on Hoth as a rebel soldier and his laser gun dish explodes. And right before Han is going to frozen in the carbonite. As Chewie, in a fit if rage, throws a stormtrooper of the ledge (barely audible).
The sound of R2-D2 moving was produced by recording the sound of a car window motor in operation.
The sound of the Tuan-tuans was produced by recording the sound of an Asian sea otter named Moda.
The sound of the snow swirling on Hoth was produced by recording surf sounds and then alternately increasing and decreasing the volume.
The entire sequence with the Wampa attack was designed to explain the difference in appearance of Mark Hamill, who had been in involved in a car accident in between shooting and had a large chunk of his nose missing. Noticeably, Kershner does not show much of Hamill's nose before the Wampa attack.
Voted #8 in Total Film's 100 Greatest Movies Of All Time list (November 2005).
According to the documentary Empire of Dreams: The Story of the 'Star Wars' Trilogy (2004) (TV) some of the asteroids in the distance are actually potatoes.
David Prowse was given lines to say in the I am your father sequence. They weren't recorded but on set he said "You don't know the truth, Obi-Wan killed your father".
Kurt Russell auditioned for the role of Han Solo.
Darth Vader was ranked #3 on the AFI's list of 50 Greatest Villains