The blood on the front of the stepdad's truck disappears.
When the dad smashes the fairy his hand has glowing blood on it but it just disappears when he grabs his throat.
The FM channel is 66.6 but FM only goes to 87.8 and is rarely used.
The two radio hosts are seen frequently cursing, despite the fact they are on live radio. This is seen throughout the film, despite the fact that even on local radio, they keep a three second delay so they can bleep any cursing out. This would also cause them to be fined heavily and there lack of control of language, would get them fired and they both would have lost there job. This just wouldn't happen in reality.
During the story with the drug dealer, he is seen selling drugs right out in the open and at a very busy party. In reality, he would not do this as Halloween is known for having a lot of cops on the street, and it's a good chance that any of those people at the party could be undercover cops. No veteran drug dealer would do this, at least were cops could catch him. This makes little sense.