While searching for the missing friends, the EMT finds blood on the hood of a car. When she reaches out to touch the blood, more blood splatters down onto her hand. When the camera shows her looking up in the next shot, her hand is clean.
When the sheriff hands his sidearm to the EMT, it is ready to fire, with the hammer already back. The EMT takes it and racks the slide, which is unnecessary since the pistol is already set up to fire once the trigger is pulled. Also, when she racks the slide, the round already in the chamber would be ejected and another round from the magazine slid into the firing chamber. No round ejects from the pistol though.
When the four friends leave their car to walk to the junkyard, it is full daylight. but after walking just the one mile, it is fully dark.
In one of the opening scenes, the broken-down teen agrees to enter the stranger's truck to warm up but the thermostat is on cool and the fan is in the off position.
The volume control on the radio is also turned all the way down, despite the loud broadcast they're listening to.