Revealing mistake: At the end when April and Kyle are killed, they are thrown in a hole back first. When they are shown, they are neatly positioned beside each other. April even has her knees bent up and Kyle has his arm around her waist meaning they obviously positioned themselves for the final shot.
Plot hole: When April and her friends are trying to get to town, the road is blocked by a huge tree. Yet later in the movie, the police arrive at the cabin they are staying in. How did they get there since the road is completely blocked off and there's only one way in and one way out?
Other mistake: At the beginning of the movie, a woman runs to the store to get help. She uses the pay phone booth outside. The UFO takes her and the whole booth. A minute later, the booth crashes back to Earth. The next morning, the sheriff finds her wallet in the debris. She wasn't carrying it and didn't have a purse or pockets.