Passport to Paris (1999)

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.

Continuity mistake: When Jean & Michel are playing their guitars on stage with their band. They see Melanie & Ally at the dance, they put down their guitars and go over to them. As the twins are talking to someone else, you can see them in the background pointing to them & getting off the stage again.

Barbara Porter: Look, I know your grandpa's not great with you girls.
Melanie 'Mel' Porter: Mom, that's like saying the Titanic's not great with icebergs.

Friend of Aly and Melanie: She was totally edging on my squeeze, so I dinged her with a bounce-bounce in the numbers lab.

Jean: You have to worry.
Michel: He means to say: you don't have to worry.