Kelly is beside the pickup truck when Ava's father approaches, then one sees little of him for an extended time during which Ava disarms and kills two members of the household, then escapes and is shot at by a third member. Kelly then appears in the house but it's unclear where he was all that time.
It's unexplained when and how the head injury to Ava occurred, it simply 'appears.'
When Max is in the pantry with Ava, he explains to her the controls mounted on the wall, while seated a distance away. There's then a closeup of his hand pointing at them from close proximity. In the next seen he is again pictured sitting at his same spot. His hand could not have been so close to the wall unless he stood and walked over to it, which he did not.
When Max shows Ava how to shoot, he stands perpendicular with the gun. In zero cases on this planet will this happen with anyone who knows about guns and gun safety. He should be behind her and out of harm's way.
When Ava's dad has his left hand caught in the trap, all he has to do is push down on the trap release with his right hand, and the jaws will pop open.
Ava's father removes her jacket and cuts off her bloodied t-shirt with no explanation, then says "You not gonna get very far dressed like that." It's unclear why neither of them retrieves her coat.
When Ava tries to escape the house in which she is held captive, she pulls on the door knob but doesn't try to turn the lock directly above the door knob.