Audio problem: After landing on Endor, Han says, "This whole party will be for nothing if they see us.", but his lips hardly move. (00:55:10)
Audio problem: When Lando is inside the Death Star we see a shot of him scraping the side of some metal. Then he says "That was too close." His voice has the same echo applied to it as the sound effects in the narrow metal tunnel. For unknown reasons this mistake wasn't even fixed in the DVD.
Audio problem: When Vader is talking to Moff Jerjerrod in the beginning of the film, he says, "Perhaps I can find new ways to motivate them." As he says the last two words, Jerejerrod's mouth is moving as if he were talking, but nothing is heard. (00:04:00)
Audio problem: When the Death Star is about to explode, Admiral Ackbar says, "Move the fleet away from the Death Star.", but his lips don't move. (01:57:30)
Audio problem: In the beginning of the space battle, a Mon Calamari says, "Admiral, we have enemy ships in Sector 47.", but his lips don't move. (01:31:15)
Audio problem: When the group in the shuttle Tyderium is waiting tensely to see if the clearance code is accepted, Han says, "They're not going for it, Chewie." If you look closely, you can see that when he stops talking, his mouth is still moving. (00:54:00)
Audio problem: When the shuttle Tydirium is approaching Endor, look closely when Han says, "Fly casual" - he begins to say the words before his lips start moving. When he stops talking, his mouth is still moving.