Revealing mistake: Just before Luke chops off Darth Vader's hand in the battle at the end of the movie, you can see that the bar has already been cut (the line is visible) to give the illusion that Luke cut through the steel bar with his lightsaber as well as Vader's hand. (01:48:45)
Revealing mistake: When Luke leaves the Death Star in an Imperial shuttle, a large girder or something falls right in front of his ship. If you watch closely, you can see it bounce, revealing the miniature. A huge, heavy girder wouldn't have bounced like this.
Revealing mistake: When the shield generator explodes, a piece of shrapnel flies towards the left side of the screen and then flies back, because it bounces off the inside of the building the miniature was housed in. (01:50:05)
Revealing mistake: When Luke and Leia swing to the skiff on the rope, in the shot from the back, Leia is obviously played by a stunt woman - the birthmark on Carrie Fisher's back, which can be seen a few times on board the sail barge, is missing. (00:35:00)
Revealing mistake: At the beginning of the ground battle on Endor, two stormtroopers are knocked to the ground by the Ewoks. In the following shot, one of the troopers has a big crack in the left shoulder of his armour. The crack was obviously not there in the previous shot. (01:34:40)
Revealing mistake: In the battle on Endor, there is a shot of some Ewoks on a catapult and the at-st fires at them. Notice the second time they get fired at, the blast hits the catapult. Just before the shot ends, notice there is no damage to it. (01:40:10)
Revealing mistake: When Vader throws the lightsaber at Luke and the platform collapses, the point where the platform's columns connect to the ceiling have expanding circles of smoke coming from them as the columns detach from the ceiling, created by the charges used to sever the platform. (01:50:20)
Revealing mistake: During the speeder bike chase scenes, speeders bikes don't affect any vegetation, even though they're flying near the ground at incredible speed.
Revealing mistake: When Luke and Vader enter the Emperor's throne room, in the shot from behind, you can see the stairs through Luke. (01:26:30)
Revealing mistake: When Leia takes a speeder to chase the stormtrooopers, there is an SFX box around it and it makes no shadow on the ground.
Revealing mistake: After the Rebels break into the bunker, a Rebel in the background punches an officer. But if you watch closely or play it in slow motion, the Rebel's hand never comes into contact with the officer's face. (01:33:25)
Revealing mistake: In the scene where Han and Lando are talking in the hangar after the big meeting about the new Death Star, right when the scene opens and the shot pans down, notice how half the hangar is real and the other half is a matte painting. (00:49:30)
Revealing mistake: When Darth Vader lands on Endor there is a shot of him walking out of the shuttle, underneath the ramp there is slight black spot which probably marked the transition from studio set to matte painting. This was eliminated for the 4K release in 2019. (01:22:47)
Revealing mistake: In many of the scenes taking place in outer space, if you look closely you can see polygon borders surrounding space vehicles (X-Wings, Star Destroyers, and even the Death Star) indicating the objects being superimposed into the outer space background. [This mistake may only apply to the Blu Ray version.]
Revealing mistake: In the wide-shot where Luke leaps from the prisoner skiff over to another skiff, you can see the stick used during the filming, which is much shorter than the regular one. The blade is not even glowing. (It is not just simply the hilt of the sabre, it's too long for that.). (00:32:15)
Revealing mistake: When Luke is in the Rancor pit, there is a Rodian in the crowd - some of his fingers are hanging from his hands. Cheap costume. He makes hand gestures like Mr. Burns - helps to find him.
Revealing mistake: After the rebels have destroyed the radar on Endor, there's a shot of Lando and a Sullustean laughing, and after that, a shot of spaceships. One Y-Wing passes in front of an X-Wing, but the light of its engines disappears a little bit before.
Revealing mistake: In one quick scene when Luke's hologram is talking to Jabba, the film has been reversed. The camera shows Jabba sucking on his 'bong' and then pans down to Salacious Crumb. However, during the Jabba shot, the air bubbles in the 'bong' are going down, as opposed to surfacing. Behind Jabba, you can see the smoke created is also going downward.
Revealing mistake: When the Tydirium shuttle is flying toward the Imperial spaceships, there's a frontal shot of it and a strange thing appears near the shuttle for a few frames. It's not the kind of marks that appears on an old film, or a special effects box. It's like a problem with the matte painting.
Revealing mistake: In the shot where Vader throws the Emperor into the pit, the Emperor is obviously a puppet, because he doesn't move at all. (01:52:15)
