For some shots of the actors in cars the windshields have been removed. Sometimes the front, sometimes the rear, sometimes both.
During the initial kidnapping and drive out into the woods, a shadow of the camera equipment can be seen on the trunk of the car in shots from behind.
Early in their hike through the woods, the teens and the Sheriff emerge from the thick trees to the side of a stream. Shadows from crew and equipment clearly move across the ground in front of the party.
Steve works for the county sheriff's department, but his shoulder patch says "police department". There is a difference.