My Theory (which is Mine)
okay , I think that I've got This figured-out , after reading One of the Other Threads !!!
the Film starts-out at the Police Station. the "Victim" (who turns-out to be the "Killer" at the End) begins telling HER Version of What-happened. We (the Audience) find-out , at the End of the Film , that She is/was totally-crazy ... therefore , there is No Evidence that All (or Any) of What the "Killer" described actually-happened ... No "Invitation" from the Other Girl's Family. No "Slumber Party". No "Massacre" of the Girl's Family (at-least as the "Killer" described-It). No "Jeepers Creepers" Truck. No Souped-Up American Muscle-Car (how could a Convenience-Store Clerk afford Something-like-That ? ).
No Big/Sloppy French Guy. No Conversation(s) between-Clerk and "Killer". No GreenHouse. No Conversation(s) between "Killer" and Police. Nothing except for a Killer and a Victim (and presumably , the Victim's Family.
Who agrees ???