Deliberate mistake: Towards the end, Roy's sunglasses keep changing, in almost every shot. It's so blatant that it must be deliberate, but there's no reference made to what might be the reasoning behind it.
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. (00:03:30)
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. (00:07:05)
Factual error: It doesn't make sense that Daniel would be researching classical music, or that he chooses Jen as his 'phone a friend' because of her apparent knowledge on the subject, because there are no topic categories on 'Who Wants To Be A Millionaire' - the questions are entirely random, Daniel would have no way of knowing one of the questions he'd be asked would be about a particular topic.