When explaining why the scarecrows did not attack them before, Scott says that, in chess, you can use a turn to promote your pawn. This is not accurate, since promoting can only be done once the pawn has reached all the way to the end of the board, not just by simply taking a turn. Scott, as a member of the chess team, should be well aware of this.
When running through the cornfield the teens come up on a mailbox and an old rusted-out car and there is corn growing up right underneath the car and around mailbox. For this to be so the corn must have been planted before the car and mailbox were put in.
When the kids are trying to hot-wire the truck, every time the engine turns over the headlights and parking lights light up, then they go out when the engine stops; that's backwards. If the lights were on at all, the load of the starter motor turning the engine over would dim them.