The Conspiracy: Tom Cruise’s character actually imagines the majority of the events of the movie while being held in captivity.
The Evidence: Cruise’s character is actually locked away, for what we perceive is a short time, in the iJail where prisoners brains, “remain free to dream.” Could it be he never left the iJail? The ending, which sees the psychics living out their lives in some perfectly idealistic cabin that looks completely out of place, lends a lot of support to this one.