The shoulder flashes on Sheriff Mooney's uniform reads "Mercer County Sheriff's Dept.", but the decal on the SUV that Mooney is seen driving reads "Davis County Sheriff".
When Clay pushes the truck with Early in it over the cliff, the truck eventually explodes in a huge fireball. But later, when the police investigate the incident, the truck is not charred by fire at all.
Shortly after the funeral, when Amanda is waiting for Clay in his bed, she gets up and a picture on the left-hand side of the headboard falls over. A few seconds later the picture is upright again.
Before Clay pushes the truck over the cliff, he's inside and he leaves the door open. But when the truck goes over the cliff, the door is closed.
When Clay is being interrogated for the first time, and he is asked if he was just friends with Amanda, he sits with nothing in his hands or mouth. When he answers "no" a second later, he has a cigarette in his mouth and matches in his hand.