Continuity mistake: Toward the end of the film while the school is on fire, Kimble's partner runs to the side door gun drawn. She is spotted by Crisp's mom and is hit by her car, knocking her down. When she arrives shortly with a bat to save Kimble she is much more banged up than when she was first struck, most noticeably a rip on her right shoulder that wasn't there before.
Continuity mistake: On Kimble's first day as the kindergarten teacher, he's wearing a white shirt with jeans and a jacket. When he shows up the next day and is talking with the mother of one kid, he's wearing a maroon shirt with khakis. They then cut to the kids doing the pledge of allegiance, then to the kid eating everybody's lunches. In that shot Arnold is wearing the white shirt, jeans, and jacket. But then, they cut to "Who is your daddy, and what does he do?" sequence, and Arnold is back in the maroon shirt and khakis. It seems the "Lunch-box kid" part was in the wrong spot.
Continuity mistake: In the scene where Phoebe is interrogating Cindy, Cindy refuses to testify or identify Crisp in the line up. She then tries to leave the interrogation room, but it's locked. When the interrogation is over, we see that Phoebe opens the same door without any problems, or anyone opening it from the outside.
Other mistake: When Det. Kimble comes out of the school on the stretcher, we see all his class gathered by his side yet still next to the school. Standard FEMA operating procedures (and common sense) would have had the kids far away from the school and not standing near the entrance emergency workers are actively using to get the fire under control.
Revealing mistake: In the shot where Dominic is falling from the radio tower from afar, he supposedly gets hung up by his backpack. However the lack of tension on the straps indicate that something else kept him from falling. We see the proper tension on the backpack when the scenes change to an up close shot.