Revealing mistake: When Natalie discovers Tosh's body, a close up shows Tosh visibly blink her eyes.
Other mistake: Why would Natalie get probation? She wasn't driving. It wasn't even her idea.
Suggested correction: Lawyer here - Not a mistake at all. She would be liable as an accessory, under aiding and abetting. The exact crime varies between common law jurisdictions, but she is laughing along when Michelle is speeding and terrorizing the other driver. In common law jurisdictions, that would be viewed as encouragement of Michelle's committing a crime (she explicitly says she didn't tell Michelle to stop), which is a form of abetting, and indeed carries criminal charges.
Plot hole: When the girl in the car gets killed she is decapitated with an axe. All you see is her noticing someone in the back of the car then a shot of an axe coming through the driver's seat window. How did the killer manage to swing an axe in a car and take off someone's head whilst he was sitting right behind her?
Continuity mistake: When the gas station attendant fills up Michelle Mancini's car, he is looking at her. The next shot shows that he's looking at her back seat.
Plot hole: At the end of the film, Brenda could not know that Nat and Paul were to drive the truck in order to wait inside it for them.
Suggested correction: Didn't Nat come there in that truck? And assuming the truck wasn't locked or lockpicking is amongst Brenda's veritable arsenal of skills, maybe she hid by the car until she saw them coming, and got in.
Plot hole: Brenda's shown to have survived at the end and is at a different college. This is never explained given she got shot, fell out a window, thrown through a car window and off a bridge into a river.
Suggested correction: Supposedly human killers surviving the impossible is a staple of slasher movies, though that doesn't really make this not a mistake. But people in real life have survived worse.
