Revealing mistake: Throughout the movie the rescue helicopter changes. The paint job remains the same but they're two entirely different choppers. This can be most easily seen by the flat single-pane windshield of one and the round wrap-around windshield of the other.
Revealing mistake: When the kids are being washed down the rapids they desperately hang onto a log across the river. As the girls climbs up, one of the branches rotates when she grabs it and is a round peg in a hole.