In season 6 episode 12 "my fishbowl" JD hands a fishbowl to the janitor so he can go into the room with Pvt. Dancer, the Janitor stands outside the door the whole time and the scene cuts back and forth...while he's standing outside the room, Notice that the door to the room swings inward towards the room, however when JD finally leaves the room, the door swings outward towards the hallway and knocks the fishbowl into the wall and shatters it.