a caller on one of the tv stations said the guy was in the theatre and took a cell phone call, but instead of going to the lobby, he went out the exit door....I surmiss he put something in the door to get back in....
sounds like the cell phone is important also.
Your comment makes the most sense.
A drink cup or popcorn box is enough to keep the door from closing enough to latch.
They may have surveillance video at these portals.
Not sure it makes a lot of difference though.