After their first rehearsal, Janey tells Lyn how she was with Jeff for over an hour. This is impossible since they are clearly only in the room for no more than 5 minutes - the same song is playing the whole time through that scene, and is still playing when Jeff leaves.
In the first dance of the movie when some dancers lay down to spell out DTV, a boy and girl in green spell out the V. In the wide shot, the girl lays down on the outside (right side of the screen) and the boy lays down on the inside and they don't put their legs together to spell out the V, they just lay down parallel. In the close up shot, they are switched and their legs are together to spell out the V.
About an hour into the film there's a montage of Jeff and Janey practicing in the park. In one sequence Maggie is sitting in a tree looking on as Jeff jumps off of it. Jeff lands and turns to look at her. The shot of her reaction was flipped, as the text on the Pepsi can she's holding is backwards, and the tree she's sitting on is now on her left (screen right) instead of her right (screen left). This was obviously done to match the direction of the shot of Jeff looking at her.