Continuity mistake: When Darth Vader and Admiral Piett are talking on board the Star Destroyer at the end of the movie, in the first shot, a man is standing behind Piett. In the next shot of Vader and Piett, a different man is standing behind Piett. Then, in the third shot of Vader and Piett, the first man is back. Widescreen version only.
Continuity mistake: When Vader is about to tell Luke that he is his father, as Luke says, "He told me enough," he is holding onto one of the thin poles next to him. In the next shot, his hand is positioned lower down and clutching the other pole. Also, his head is in a different position, seen from the markings on one of the other poles. The position of his head and hand changes in the next shot as well. (01:46:35)
Continuity mistake: Leia and Han become annoyed with C3PO's chattering, and Leia turns him off. However, if you watch him in the background, you can see his body move as he breathes.