Other mistake: Tower Air never had direct flight service to Boston, only to NY from LA.
Other mistake: In the song "A Rumor in St. Petersburg," according to the closed captioning, the characters sing the words "no proof of fact." According to the lyrics in the soundtrack booklet, they are actually singing "or through a crack." And if you listen, it's actually what they are saying.
Other mistake: In the scene where the Professor and Sara are fighting the bad guys, Will Wheaton throws an ashtray at the Professor. Before the ashtray gets to him he sprays his rear end with the liquid flubber from the squirt gun. When he does this he sprays his jacket, which at that time is covering his rear. When he jumps and hits the ashtray, the ashtray does not hit his jacket, but his pants. According to the movie, flubber in any form needs to come into contact with the object to bounce back.
Other mistake: During the Cyborg Master's attack on the police station, the bald cop goes to get a gun out of the gun storage room - which is a regular closet. It's not even locked, he just walks straight in. No police station in the world would be that careless with their weapons.
Other mistake: During the honeymoon scene, Tia (who is obviously wearing a wig) and Kevin are rolling around simulating love making. What ruins the mood for me is when strands of her "hair" come loose and are lying around on the bed. It sure would dampen my mood if someone pulled out chunks of my hair.
Other mistake: Towards the beginning when someone is looking at a newspaper about the airliner being blown up, there are nonsense articles on the paper and pictures of people that don't match the names under them. With some white guy's picture over the name Michael Jordan on the left of the page, and then on the right a picture of a white woman with the name Will Smith under it.