Continuity mistake: When one of the stormtroopers unties Han Solo before he is put into the carbonite, watch his wardrobe - he has a disappearing / reappearing jacket on. This is fixed to an extent on the DVD - the jacket is now lightened to almost match his shirt, but it's still shiny like leather. (01:32:05)
Visible crew/equipment: Chewbacca enters the "junk" room to collect the remains of Threepio, and in the close-up scene of Threepio's head on the conveyor belt, you can see a reflection of the camera and several of the crew. (01:23:10)
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)
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)
Continuity mistake: When Han and Leia kiss in the Millennium Falcon, Leia's arms are around Han's head in the wideshot, but not in the close-up. (00:49:55)
Continuity mistake: When Vader is seen in Cloud City, Lando says, "I had no choice, they arrived right before you did" and two of the stormtroopers on the lowest step are standing about a metre apart. In the following close-up of Lando, they are standing so close together that their ankles are touching. This can only be seen in the widescreen version. (01:25:05)
Trivia: In Cloud City, when Chewy finds C-3PO in pieces in what looks like a droid scrap room, you can see what looks like the upper half of IG-88 leaning up against the wall. It is revealed later in books to be the IG-88 unit that went in search of Han, but was intercepted and destroyed by Bobba Fett.
Continuity mistake: When the stormtroopers push Leia into the cell in Cloud City, she is wearing a completely different outfit from when she was taken captive. (01:25:20 - 01:28:35)
Continuity mistake: When the Falcon is being pursued by the Star Destroyers after escaping Hoth, C-3PO enters the cockpit, attempting to talk with Han, but the ship shakes and he lands on Chewie. After Han says to check the deflector shields, Chewie pushes C-3PO off him, though C-3PO leaves his hand on Chewie's shoulder. In the next shot, C-3PO is suddenly standing at the other end of the cockpit, with his hand nowhere near Chewie.