Other mistake: In the beginning of the movie, when you first see Mary-Kate (aka Mel) and Ashley (aka Ally), Mary-Kate walks off without ever closing her locker.
Other mistake: When Mary-Kate and Ashley arrive at the dance, the two boys are up on stage with their band. They are both playing the guitar, but when they see the twins they put down the guitars and go to see the girls. The thing is that the music sounds exactly the same before they leave as after they leave.
Other mistake: When Mary-Kate and Ashley are jumping and fighting on the bed, listing to music, a pillow falls off the bed, then in the next scene they are still jumping and the pillow was up on the bed again.
Other mistake: When they are changing Rodin Museum To Luxembourg Gardens, they type in an H, but there aren't any H's in Luxembourg Gardens.