Other mistake: At the end when Vanessa is sitting in the deckchair outside her Grandmother's caravan, she asks the cops if they have a cigarette. The view cuts to the cops who smile at her and chuckle; when the view cuts back to her, she grins and you can see a faint plume of smoke rising from below the camera, indicating she already has a lit cigarette. She didn't light one at any point either.
Vanessa: Ho-ly shit! Well look who got beaten with the ugly stick. Bob, is that you? My God, I can't believe such an itty bitty gun could make such a big mess out of someone! You are so ugly Bob! Oh and hey I heard you have one of those poop bags where the shit comes out the side, you're just a big old shitbag aren't you Bob! I hope you think of me every time you shit in that thing, motherfucker!
Question: Why does Bob Wolverton have a psychology manual in his car when he's a children's psychiatrist?