Stupidity: In the opening scene with the military convoy, the two soldiers in the lead vehicle never notice the car veer into their lane, even though their faces are bathed in bright light from the car's headlights. They simply ignore it and keep talking to one another.
Stupidity: When the 1st girl gets sidetracked and then locked in the room to die, she escapes and doesn't bother telling anyone what he did (even though she had a whole lot of time to say more than "run, run").