Continuity mistake: When Hallie and Annie are in the isolation cabin, you see the bucket that the water is dripping into from the leak in the roof, on a stack of books. After the wind blows all of Hallie's pictures off the wall they are sitting on the ground picking them up, Annie is seen picking up Hallie's little animal (Cuppie) right next to the bucket of water, which is now on the ground with no stack of books to be seen. (00:29:07)
Continuity mistake: When Annie and her friends are approaching the area where the fencing is taking place, all three girls are holding tennis rackets. The shot switches to the camp counselor and back to the girls. The African American girl is no longer holding a tennis racket. The shot goes back to the counselor and then to the girls again, where all three have a tennis racket again.
Continuity mistake: In the car, before entering her mother's house, Annie is wearing a plastic watch, but when she hugs her mother she is wearing a metal watch.
Continuity mistake: When Hallie and Annie get out of the water bin after their fence match, they both take off their helmets, revealing Annie's messy hair. In the next few scenes, you see the hair a little less messier than before and neatly pulled back.
Continuity mistake: When Annie is entering her home in London, she puts her hand on the doorknob and pushes the door open. In the next shot when it shows the entryway with the door opening, there is no doorknob.