Revealing mistake: Watch the background fighters during the club scene; there are many occasions where you can see the actors are just waiting to get hit or fall down, most notably when the little kid is fighting the guy in the camouflage. A "fighter" up on stage is standing there with his arms up as a kid winds up a kick.
Revealing mistake: The fire escape is already lowered before the boys begin to walk down it, but it starts to lift up before the last boy steps off; someone must have been holding it down for the boys to descend, then let it go to get out of shot, thus allowing it to raise up.
