Corrected entry: The band that is playing at the dance is the Offspring. It is pretty fitting that they are playing the song "beheaded", seeing as the singer gets his head taken off.
Corrected entry: When Anton first goes to his friends' house, they ask him why he hasn't heard of the Halloween Dance. The guy in the red shirt tells him that if he "had been in school the last six months..." As Halloween is in October, no one would have been in school the last six months, only the last two. And a Halloween Dance probably wouldn't have been planned before the end of the previous school year.