Star Wars Episode 6: Return of the Jedi - Boba Fett's Antenna
In Jabba's Palace, when we see Boba Fett just standing around, his helmet antenna is on the right side of his head. Later, however, when the action starts, we see another shot of Boba with the antenna on his left side.
This is because the film was put on the reel backwards. If you look carefully, you can see where this happens to Vader. You can tell because of his life support pack on his chest.
Yes!!! I have noticed this same bloody problem since I was about 10 years old and it has always bothered me; especially when it was not fixed in the THX reissue or the Special Edition! This can be solved by a simple flop in Photoshop with a digital image and only takes a few seconds. Erg!