As Adam (the clone) runs out the back door of the school to chase after the bad guys who have just kidnaped his wife and daughter, we see the door closing slowly behind him.
Then the camera cuts to a shot of the SUV and the helicopter which the bad guys are making their escape in.
After a few seconds the camera cuts back to Adam (the clone), and behind him we can clearly that the door he had exited from just a few second before is now completely closed.
Then, the camera cuts back again to the SUV and helicopter as one of the bad guys fires his (laser?) gun at Adam.
And once again the camera cuts back to Adam (the clone) as the shot which had just been fired at him hits a part of the building next to him and explodes.
As Adam (the clone) ducks away to dodge the explosion and debris, take a close look at the door behind him (the same one he had exited from in the first shot).
Mysteriously, it is once again closing itself.
Was it a ghost? Or maybe it was just poor timing of the scenes choreography during multiple re-takes. You decide.