You dress in black, like half of the movie goers. You park your car (illegally but who cares about a ticket) just yards from the emergency exit. All of your tactical gear is staged in the trunk, in the order of strapping it on. You leave the theater and put a piece of duct tape over the latch mechanism, go to the trunk, put on your gear, and return within two minutes.
This does not take the CIA to pull off. Remember, this kid may be a loon, but he’s a very high IQ loon. Phi Beta Kappa in a hard science, on merit scholarship.
Okay, I’ll buy that. I wasn’t picturing him going out to his car to get this stuff. I had assumed that would be too far away and that he’d have to stash it in a hallway. If he just went to the trunk of his car and suited up, then I can see how it would be easy.