Helicopter Scene at the End **SPOILER**
Why would the pilot pick up Ava and leave without Caleb since Nathan said that the helicopter was scheduled to pick up Caleb at 10:00 am on his last day? We don't hear what Ava says to the pilot to explain Caleb's whereabouts but I found it strange that the pilot wouldn't have verified her story before leaving without Caleb.
Otherwise, this was a great movie.