Other mistake: When Jack asks Greg to throw a brick at the RV window and it hits the car windshield Dina and Pam pop their heads out of the RV door looking shocked. In the next scene Pam and Greg are walking into the RV like it's the first time, seems like Pam wouldn't have that reaction to the RV if she's already seen it.
Other mistake: The DVD release was created with a "pseudo widescreen" as various scenes cut off major action. The most obvious is in the beginning of the film when the main character meets the crazy girl. Her head is framed bottom right but the widescreen completely cuts off the crazy girl's head. This can be explained by the enormous aspect ratio of the original film, which is bigger than standard (USA) widescreen, that or a bad transfer.