Continuity mistake: After Luke crashes during the battle on Hoth , the AT-AT is far away from him and is moving rather slowly. A few shots later, the AT-AT stomps on his snowspeeder, but it was too far away from him in the previous shots to reach it that quickly. (00:29:55)
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. (00:33:00)
Revealing mistake: Right before Luke nicks Vader in the shoulder with his lightsaber, Vader cuts through a railing. There's a hole in the railing exactly where Vader apparently cuts it. Also Vader's lightsaber never comes into contact with the railing, yet it sparks. (01:50:15)
Revealing mistake: When Luke and Vader are fighting in Cloud City, there is something looking like tape wherever they hit something with their lightsabers. Maybe it's pyrotechnic charges?
Continuity mistake: When Luke is doing a handstand and has the vision of Han and Leia, in the last close-up of him upside-down, his elbows are bent, but in the next shot, his arms are fully extended. (01:14:05)
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. (01:50:05)
Continuity mistake: When Han first walks into the command center on Hoth, there's a shot of Leia looking at him. The shot has been flipped. This can be seen, for example, from that the men on either side of her have switched sides. (00:04:50)
Other mistake: When the Star Destroyers are seen for the first time, in the second shot, some of the TIE fighters that fly over a Star Destroyer are transparent. (00:19:55)
Suggested correction: Just loaded up Disney+. I watched that scene - all the Tie Fighters are not transparent. What you're seeing is light set used to light up the Tie Fighters in space, to give the illusion that the Star Destroyer engines are shining on them.
Continuity mistake: After Vader cuts through the poles at the end of the duel, the burn marks keep changing size and appearance between shots. (01:50:25)
Continuity mistake: At the end of the movie when the Millennium Falcon is escaping from the TIE fighters we see some going after the Falcon then we see a shot of Vader looking at it - there are now no TIE fighters. They had no time to escape away. (01:57:45)
Suggested correction: Actually, the TIE fighters are still there. They're just too small to see.
Continuity mistake: After Luke's hand gets cut off, in the wide shot where he first comes to a stop after going down the tunnel, you can see his hand. (01:47:55)
Continuity mistake: When Leia is briefing the Rebel pilots, some of the men behind her change position between shots. (00:24:00)
Continuity mistake: When Ben appears to the injured Luke (on Hoth), Luke is reaching out with his left hand calling, "Ben. Ben." As Han appears, Luke is found with his right arm reaching out. (00:13:35)
Continuity mistake: After Han is frozen in carbonite, the outline of his shirt indicates that he is wearing a different shirt from when he was frozen. It isn't the shirt he's wearing after being unfrozen in "Return of the Jedi", it looks more like the shirt he was wearing in "Star Wars". (01:36:00 - 01:37:10)
Audio problem: When Luke is about to leave Dagobah, he says, "But Han and Leia will die if I don't," but the words don't match the movement of his lips. (01:19:45)
Audio problem: At the beginning, when they close the door of the hangar, it makes no sound on the first shot. (00:11:45)
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. (01:43:15)
Revealing mistake: When Darth Vader meet Luke in the Cloud city, you can see the stick used to make the special effects before Vader starts his lightsaber. (01:41:05)
Audio problem: When Chewie is choking Lando, Leia says "We understand, don't we, Chewie?" A shot later, her mouth moves but no sound is heard, and when she says "We don't need any of your help", her voice is heard a little bit after she starts moving her mouth. (01:42:20)
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. (01:18:45)