Revealing mistake: As Vicky and Burt are driving down a dirty lane, through a row of corn, you can see fresh tire tracks in the mud from a previous take. (00:34:35)
Revealing mistake: When Vicky throws the lamp at the children, there's no power cord attached to it.
Revealing mistake: When Burt hits one of the children, the skid marks are in front of the car, when they should be behind it.
Answer: For letting the two adults into the town and disrupting the pact they made.