1. why not shoot him or stab him when he was down?!? hitting his back with the rifle twice wont do anything. I know it's difficult to comprehend how you'd act and feel in their shoes, but I hope I'd have the common sense to kill him. I wonder what audiences would say after a film in which the hero actually did kill the killer half way through, and the rest was other struggles e.g. escape, finding frienRAB, other killers?
The rest are just observations, many mentioned already but frustrated me to the point of writing them down again:
2. why drive the car off the cliff, only to go back to get another car, duh. furthermore, why hide on the cliff in the same path as the car you just pushed down?
3. why climb back up the cliff and lay there, screaming and talking at the tops of your voice. The killer is around... SHUT UP!
4. why say "i'll be 5 minutes" and then spend 20 mins watching peoples' videos?
5. I didn't understand why he just killed the girl on the side of the road by shooting her, after she fell out of the car. This is a guy that seems to scout the area, hoping for fresh meat and, when getting some, savouring his time killing them. Why would he kill her like that instead of taking her back and torturing her?
apart from that, beautifully shot, some originality, and very realistic