Continuity mistake: During the horse and buggy ride to the church through downtown New York, when one of the girls is holding the reins by herself, you can tell there is a person under a red blanket at her feet (I guess to protect her while filming in case something goes wrong,) and only a moment later, the same blanket is black.
Other mistake: In the scene where Alyssa's father is in her room, she says "Ms. Kensington seems nice. Does she work with you?" Then she holds on to the bedpost and sort of swings herself around it while looking up at the ceiling with her tongue to one side of her mouth-she probably thought it was just a practice shot. She does the same thing in the scene where she is on the pottery wheel with Diane-she quickly looks up towards the camera.
Continuity mistake: Amanda spits the snail into her left hand, but when she turns around it's in her right hand.
Plot hole: In the scene where Steve Guttenberg runs to the lake to wash off the mess from the food fight, Mary-Kate and Ashley Olsen come from their hiding place behind a canoe, to the canoe rack, where they can see whats going on without being seen. Kirstie Alley is still near the mess hall and she would have seen the girls.
Continuity mistake: Very early in the film, a street stickball game is interrupted by the arrival of a taxicab. As the cab approaches, it is a Chevrolet. As Diane and Amanda enter the cab and it starts to drive away, it is a Ford. As it continues to drive away, it is a Chevrolet again.
Continuity mistake: When the kids swap homes early in the film and the one in the orphanage is discovering "sloppy joes" the mess on her face goes from heaps to only a little.