Plot hole: Derek, who escaped the mental hospital by pretending to be his twin brother Tyler, was able to locate Tyler's vehicle by using the keys to beep its horn. Once inside the SUV, he apparently found Tyler's cell phone, which is odd because most people carry their cell phones with them. But Derek did not ask Tyler for his cell phone's password before rendering him unconscious - so how did he gain access to the cell phone without the password? (It isn't likely that Tyler previously gave it to him). (00:20:40)
Suggested correction: Tyler never left his cell phone in the car. He had with him when visiting Derek. We see him pull out his cell phone to show Derek a picture, so the phone was already unlocked, assuming he locks it with a password in the first place.
I haven't had time to finish posting the rest of the mistakes I have, but I just uploaded two that should show up under "pending submissions." They probably should have been posted before the one above. I suppose the real question is where the cell phone came from each time.