Audio problem: In the carbon freezing chamber, Han says to Chewbacca, "The Princess - you have to take care of her". When he says, "You have to take care of her", his head is shown from behind, but the motion of his jaw doesn't match the words. (01:35:35)
Continuity mistake: When Han is put on the platform during the carbon freeze sequence, Darth Vader and Boba Fett are standing behind him and there is no one else in view, but when we see a close up of Han, an Imperial stormtrooper has suddenly appeared. (01:35:55)
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)
Continuity mistake: Before Han is frozen in carbonite, you can see there is nothing by Leia. When the platform Han is standing on begins to drop, we return to Leia and she now has an Imperial stormtrooper standing by her. (01:36:10)
Continuity mistake: When Luke first meets Vader in Cloud City, in the shot from behind him after he walks up the stairs, his arms are positioned differently from the previous shot. (01:36:55)
Other mistake: After Vader cuts through a pillar with his lightsaber in the beginning of the duel, the hole in the pillar is much bigger than it should be. (01:37:35)
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. (01:37:55)
Continuity mistake: When Chewbacca is choking Lando, as Leia says, "We don't need any of your help.", Lando is standing on his knees. In the next shot, only his head can be seen, but the position of his head and Chewie's arms shows that he is now standing straight up. In the next shot, he is on his knees again. (01:38:15)
Continuity mistake: After Boba Fett's ship, Slave 1, takes off, there's a close-up of Leia's face. In the background, Lando can be seen standing erect, putting his hands on his waist. In the next shot, he's crouching, with his hands in front of him. (01:39:25)
Continuity mistake: When Luke and Vader are fighting in the carbon-freezing-chamber, Vader says, " You have learned much, young one." Their light sabres are held in different angles between this shot and the previous and following shot. (01:39:40)
Continuity mistake: When Luke summons his lightsaber 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. (01:40:25)
Continuity mistake: Widescreen version: When Luke and Vader are fighting in the carbon-freezing chamber, as Vader says, "Only your hatred can destroy me.", the hose hanging from the ceiling behind Luke is pointed straight down, but in the previous shot, it was bent. This has nothing to do with camera angles - watch the smoke coming from it, it changes direction as well. (01:40:40)
Visible crew/equipment: When Luke and Vader are fighting in the carbon-freezing room, in the wideshot after Luke does a somersault, a crew member is visible in the steam on the right side of Vader, moving out of the way. (01:40:50)
Suggested correction: It's Luke, not a crew member.
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)
Continuity mistake: During the first scene in the lightsaber duel, Luke is holding his in different angles between shots, depending on the camera angle. (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: When Luke is sucked out the window, there are no wounds in his face, nor when he hoists himself up on the platform. But when he runs into Vader again, there are. (01:42:35 - 01:45:10)
Revealing mistake: In Cloud City, Lando, Leia and Chewbacca are running to the Millennium Falcon, and when then they run into a door after Leia shoots a stormtrooper, a white rubber sole can be seen under one of Chewie's feet. (01:42:40)
Revealing mistake: Before Lando warns the people of Cloud City that the Empire has taken control of the city, Leia shoots a stormtrooper. The burn mark can be seen on the troopers armour before the laser beam hits him. (01:42:40)
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)