In the first major swim meet scene, Steven and Diane are first seen standing side-by-side in the bleachers cheering. It then immediately shows Steven walking back to Diane carrying a bag of popcorn.
Near the end of the movie where Justin goes to apologize to Amy, the shots of the front porch include a giant white sticker on the mailbox that reads "NO JUNK MAIL" - however, on the close-up shot, the sticker is missing from the mailbox.
Monica's head wound originally appears on the top center of her forehead, but in a later scene at the diner the wound is now in a different location on the left-hand side of her face.