Deliberate mistake: When Shorty is showing Cindy some moves and they are doing the "Right, left, right, left" move, you can see three people walking right behind them. Then, suddenly, the people are gone without the scene being cut. The director has simply just overlapped the scenes while they are doing the moves.
Deliberate mistake: When spoofing Charlie's Angels, the chain that Cindy grabs a hold of as she jumps over the gate wasn't there when Hanson jumped through the gate. It seemed to just appear. This also happens with the baseball bat Hanson uses. It isn't there, until he needs to use it to hit Cindy.