Big-Lipped Alligator Moment: A few examples. The first example would have to be the dancing teams and the "Snaps" competition taking place elsewhere. Secondly, there is a scene with a couple of drunk guys deciding amongst themselves to "kick his ass" (the person whose ass they would kick is not entirely clear), complete with Michael saying, "Cut!". Third, one scene has a character that, while escaping from Harry, starts speaking with a Jamaican accent for no reason whatsoever. Needless to say, these scenes are never mentioned again.
Idiot Plot: The characters spend most of the movie either running in fear of the killer and criticizing/insulting each other, even though they outnumber him thirty to one and could probably tackle him if they got their heads on straight and performed a Zerg Rush. Even when they have a chance to leave when they find a car, they continue to insult each other instead of just driving away or even checking if the car works.
For example, the blood that comes out of people when the hatchet connects. Oh, and how, after Brian dies, his face looks like it was run over with a vehicle and is covered with what looks like splotches of lipstick.
The only time we see the killing blows are when the hatchet hits. Rock is killed with a baseball bat, but the camera fades out before the hit lands.
When a group of teens' car runs out of gas, you can audibly hear the brakes.