I think there is a logical problem while Evan is in Jail. The Moment he wants to prove that he has contact with Jesus, he goes back in time, Paints a Picture of the Nazis and hurts himself. So when he comes back, he's got the scars in his hands, and Carlos(I think that was his name) can't belive his eyes. BUT if Evan hurt himself in the past, he must have had the scars all the time from the kindergarten-scene to the jail-scene, so he also had the scars when he entered the jail, so Carlos should've said something like "you've had these scars all time along. Nothing changed" because it's only "new" to Evan.