Other mistake: When Mitch, Frank, and Beanie decide that they are going to have a party they say the party is on a Friday night. When they show the outside of Mitch's house you see the sign for the party and it says the party is on Thursday at 9:00. Then when Frank talks to the guys with the beer bong he says that tomorrow he has a nice Saturday planned. If the sign is right then he would have a pretty nice Friday.
Other mistake: When Mitch arrives to find the house boarded up, a note is attached to the door. However, the voiceover and the note begin differently. The note begins as 'Dear Mitch, the house is boarded up...', but the voiceover starts with 'Dear Mitch, if you're reading this, you already know the house is boarded up...'.