Factual error: When Caleb is entering the estate in the helicopter, the pilot mentions they had been flying over the estate for the past two hours, indicating that it was two hours to Nathan's house plus any time elapsed after that conversation. Calculate another two hours minimum back to the airport. The Eurocopter EC 130 pictured in the film has a maximum range of about four hours max. The helicopter quite possibly could've crashed before reaching the airport to refuel. (00:02:01)
Continuity mistake: After signing the non-disclosure agreement, Caleb drops the pen on the right of the pad on the desk. In the next shot the pen is almost in the center of the pad. (00:10:10)
Continuity mistake: The last power outage resulted in all the facility's doors being locked open. But in the final scene, Caleb gets locked inside.
Chosen answer: He inserted his own card in Nathans computer. Also, there was no mention of a power failure, only a red glow. This would be a different event than he's programmed the system for.