Other mistake: Louella Parsons walks out of a screening of Citizen Kane before it ends, but later tells Hearst that Rosebud was Kane's sled. She shouldn't know that, because the identity of Rosebud is only revealed in the final scene of the movie. And if she disliked the movie enough to walk out on it, it's improbable she went to see it a second time.
Other mistake: The chain "securing" the lock on the boarded up "Metro Christian Shelter" is in some inexplicable way on both sides of a 4" board that is taut between two other parallel boards. However, when the men are using the bolt cutter, the right side of the chain extends from a hole in the middle board, and the left side goes around the side of that same board and then around a pipe that is not originally there. The board that is to the left is missing. (00:17:17)
Other mistake: Tom Ripley's ticket says first class in the limo, but when he boards, the rich girl says she saw his stuff in the third class stack. Dickie also says that he's a third class mooch, but according to his ticket he rode first class, so that'd make him a first class mooch, not third. His cabin is never shown. (00:07:20)
Other mistake: Tony Clifton comes on the 'Taxi' stage accompanied by two prostitutes. He introduces one as Melonia, squeezes her breasts and asks 'how is our produce department?' The German subtitles read 'production department'. (00:44:25)