Revealing mistake: When one of the civil cops knocks at Jimmy's door it is obvious that someone behind it (from the movie crew) opens it. He doesn't knock hard enough to make the door slide open by itself. (01:47:45)
Revealing mistake: When Jill and Cynthia meet by the water towards the end, Jill produces her gun and is told to throw it in. As she's holding it you can see the base of the grip and there's no magazine in it - hardly the most effective weapon... (01:26:45)