Continuity mistake: When Leia is briefing the Rebel pilots, some of the men behind her change position between shots.
Revealing mistake: After C-3PO gets shot, as Chewbacca walks over to the door, his right foot crushes one of the steps on a small set of stairs.
Continuity mistake: After Vader cuts through the poles at the end of the duel, the burn marks keep changing size and appearance between shots.
Revealing mistake: Right before Luke nicks Vader in the shoulder with his lightsabre, Vader cuts through a railing. There's a hole in the railing exactly where Vader apparently cuts it. Also, if you play it in slow motion, Vader's lightsabre never comes into contact with the railing, yet it sparks.
Revealing mistake: After Chewbacca pulls R2-D2 away from the power socket, he runs away, and you can see white rubber soles under his feet.
Continuity mistake: Widescreen version: When Leia, Han, Chewbacca and C-3PO are first walking through Cloud City, as Han says to Lando, "You sound like a businessman", Chewbacca is walking behind Leia. In the next shot, he is ahead of her, and then seems to walk to the side to wait for her. In the following shot, he is behind her again.
Continuity mistake: When Vader and Luke are duelling on the catwalk over the chasm, Luke lies on his back after he falls. In the first shot, he is lying in front of the steps leading to the round part of the platform, but when he rolls sideways a few seconds later, he is lying on that part of the platform.
Continuity mistake: After Luke's hand gets cut off, as he's going down the tunnel you can see his hand.
Revealing mistake: After the headless AT-AT begins to fall over, watch its back leg on the right side of the screen. You can see a broomstick being pushed up from under the set. It raises that foot up in order to ensure that the AT-AT falls to the left side of the screen.
Continuity mistake: After Leia, Han and Chewbacca walk down the stairs in the carbon-freezing chamber, as the shot ends, Han is turning towards a stormtrooper behind him. In the next shot, he is turned in a different direction, and Leia's head is facing another way. The position and existence of some of the people around them changes between the two shots as well.
Continuity mistake: When Lando releases Leia and Chewbacca, as Leia says, "What do you think you're doing?" her body is turned in a different direction from the previous shot, and she's holding the blasters differently.
Continuity mistake: When Vader cuts through three poles at the end of the lightsabre duel, there are different poles in the shot where he cuts through them and the next shot where they fall.
Continuity mistake: When Vader cuts through the three poles at the end of the lightsabre duel, Luke is crouching down next to them. In the next shot, he is standing upright.
Continuity mistake: During the escape from Hoth, C-3PO is far behind Han and Leia as they are running to the Millennium Falcon after the cave-in blocks their path. When they reach the door, he is much closer to them.
Continuity mistake: After the carbonite block is pulled out of the carbonite freezer, there's a close-up of Leia leaning towards Chewbacca. In the next shot, she is not leaning on him, and then Chewie pulls her towards him again.
Continuity mistake: When Luke summons his lightsabre back to his hand during the duel, he's holding onto a hose with his other hand. He is holding it differently from the previous shot.
Audio problem: When Luke and Vader are fighting in the carbon freezing room, at one point Luke forces Vader off the side, looks around, then jump down himself to look for Vader. Listen to the sound that is supposed to be the sound of Luke's feet hitting the ground; you can see Luke stand back up after jumping over the side in the bottom left corner of the screen, but Luke is almost full stood back up when we hear the sound of his feet hitting the ground.