Another Dark Knight blooper

[Brandon]

This may very well have been mentioned before, but I was just wondering if anyone noticed another blooper in The Dark Knight that I saw this morning: in the scene where the Joker is walking out of the hospital in the nurse's uniform, and the explosions are going off behind him, etc., as soon as he jumps into the back of the school bus and it pulls away, there is a crew member in the back of the bus that reaches up and switches off a light or something, then slowly lowers himself back down below the windows, out of sight. He looks like a crew member because you can see some kind of headset/earphones on his ears. This happens at 1hr52min in.