Other mistake: The chunk of hair that Ted has in the car is in a ponytail, and much longer than the hair cut off in the door.
Other mistake: Tony Danza's character introduces himself as "Tony." When the credits are rolling at the end of the movie, we see that his character's name is Terry, not Tony.
Other mistake: Early in the movie, Sir Gawain gets on his horse, in a full suit of armor, by himself. Later, he is hoisted onto his horse by what looks like an early design for a crane. Armor is heavy and Sir Gawain would have to be hoisted every time he wanted to ride with armor on.
Other mistake: In the beginning of the movie, when the mechanic is working on the car on the lift, he says he has to change the oil in it, the chassis drops to the ground, there is no engine attached to the chassis or body. In addition, he is changing the oil at the rear axle.
Other mistake: In the scene where Hightower flips over the police car, if you look carefully after the car is flipped you will notice the car has no engine. Thereby making it easier to completely flip over than a car with an engine.
Other mistake: After the early truck chase, Axel arrives at the police station. He walks through a glass door that reads 'Investigaton Operations Division' which is missing the last 'i' in the first word, exactly as I've typed it here. (00:08:10)
Other mistake: When Ralph's Renault R4 goes head on into the shallow and rocky river it emerges without a dent. (01:18:45)
Other mistake: Stripe manages to get the TVs and video camera working in the department store even though Kate hadn't turned the power on yet.
Other mistake: The scene in the bookstore is shot in reverse, which although humorous, isn't a mistake. The mistake is the fact that what the characters say and what the subtitles say don't match up. When speaking the character's dialogue comes out all garbled, and when a name is brought up in the subtitles there is no reference to that person's name in the conversation. (00:47:10 - 00:48:15)
Other mistake: After the guys decide to rent the building, the shot of New York from the park is the very same one, though with different sky colour, to that of the moment when they are about to battle Gozer. Though it's a very wide and common shot of the park, the very same people are laying on the grass in the very same position in both shots (big screen recommended to spot it). (00:16:45 - 01:18:35)
Other mistake: When she breaks the TV's with her "voice" they pan to the salesmen. The glass display case is intact. Had her pitch actually been able to break glass the display case would have gone as well.
Other mistake: The very last scene of the movie shows Supergirl flying underwater holding the Omegadron. Oddly enough, though her body is realistic, her arms are now very thin and measure two meters long.
Other mistake: Jackie and Yuen assault the first bikers very fast and suddenly: despite that and the presence of crazy bikers roaming the place, a huge crowd had already time to assemble in mere seconds making an orderly circle around them, no empty spots, to witness the fight and the breath-taking stunt filmed in the wide shot. (00:16:40)
Other mistake: When they're walking on the Tri System, you can see the wrinkles in the fabric used to create the foggy background.
Other mistake: At the beginning, when Rosie strips down to bathe in the lake, only her skirt comes off, revealing her bare bottom. But not her blouse.