I didn't notice this first and picked it up on the commentary on the DVD, but I digress: In the scene where they are on Truth or Date, watch for the shot where Renee is asking the question (I forget which one exactly) but her hair goes from light and curly to almost straight and flat against her head.
Before the comments start, I am a true Kevin Smith fan, and yes I know it was shot on a different stage as the rest of the movie.