Interesting, but the most stupid thing always happen in horror movies: the killer falls after take shots or been smashed for something heavy; so there's him, dead on the flooground, no breathing, no moving. The survivor ALWAYS go check the damn body. ALWAYS!
Why just don't take a bazooka or anything sharp (as the boy did in F13th P4) and kill make the mofo into pieces?
Why they just don't runaway, as far as they could?