When the mug falls onto Todd's head. The phone is face down.
But later on when it shows the perspective of the Alec and Mindy the phone is face up.
At 0:16:30 -Greg takes 2 10mg tablets of Ambien which is twice the maximum dosage for an adult male. He would have passed out within 10-20 minutes.
When Greg puts a bag over the girl's head, her hands are not bound. She could easily rip a hole in the bag.
At 1:00:34 -with the lacrosse stick removed the closet door would have opened because of Greg pounding on it, and phrogger boy would have been caught.
At 0:32:38 -2 different head wounds would have been noticeable.