Acting for Two: A minor example. Jonathan Breck, who plays the Creeper, also appears as the bald cop towards the end of the film.
Development Hell: The third film was stuck here for years, not least because of certain ugly issues about the writer/director's past.
Enforced Method Acting: Justin Long and Gina Phillips didn't see the Creeper truck for the first time until they were on-set. In addition, Jonathan Breck made sure he didn't meet either of them until they were all on-set together.
Reality Subtext: Victor Salva, the director, was previously arrested for performing sex acts on underage boys. The first film in particular makes for a much different watch with this knowledge.