Continuity mistake: When Roy and Moss are in the basement talking about the night before, just before Jen comes in and we hear her laughing, Roy has the wooden stick from his coffee hanging out of the corner of his mouth. In the next instant shot showing the side of his face, as Jen walks through the door, it has gone.
Continuity mistake: The security guard (the guy Jen fancies) is sitting on the couch reading a big thick book. The first two shots show him holding the book from underneath, a few pages in. The next shot, his hands have changed position and he has instantly read through to almost the end of the book.