This episode was nonsensical. There were a lot of scenes that paid homage to popular movies (Ghost Busters, Close Encounters, Psycho, and Taxi Driver). The episode overall was disjointed (probably because the writers were trying to work in the movie references) which seemed to be more important than a coherant story. If you skip this episode, you won't miss anything.
Okay, it's silly, yet it's just what I want to see when I watch Jump Street. There's a problem with arson at a high school, which is serious business, but the gang has great fun with this Halloween episode. I laughed out loud with the whole 'Close Encounters of the Third Kind' visual references. Most disappointing -- apparently Johnny Depp's riff on channeling Jim Morrison during a seance has been completely edited out of the DVD version. What were the editors thinking??