Deliberate mistake: When Mary gets to the school where she is going to be teaching, all the children are standing outside wearing shoes. However when they come in to the school they are barefoot. I have a feeling this was done to show how poor the community she was teaching in was supposed to be, but it looked like too cold and rainy of a day to let the actors be outside barefoot.
Deliberate mistake: After Rockford pulls into the gas station and wipes down the windshield he speeds away to lose the tail. When he passes the park bench it's a flipped shot, then when the tail passes the park bench it's another flipped shot. (00:18:15)