During practice for the film, Rick Moliterno (one of the stunt riders for the film), broke his leg. This was written later into the film, when Cru is about to start the Helltrack race, but Rick, sitting on Christian's truck, asks him to sign his cast.
Bill Allen performed one bike stunt in the film, and that's when Cru crashes through the fence on his paper route to notice the Helltrack advertisement, but there were two guys on wires pulling on the fence.
According to co-writer Sam Bernard on the behind-the-scenes commentary, the positions of the trainees were covered up in the credits because the Writers Guild of America wouldn't let the crew put them in. Originally, "Trainee script writer" was written, but it was pulled at the last minute, worrying they could be fined.