Propofol, the drug that House asks for at the beginning, to try to knock down the patient, is a white liquid and it is for intravenous administration.
When the man shoots the other guy in the leg, no shell is ejected nor does the slide blow back just as a real gun would have.
Several times, House is actually holding the very weakened perpetrator's right arm (which is holding the gun) as he administers shots, but never once simply bends it backwards to disarm the man. During those times, the gun is pointed at the floor, so no one was in immediate danger.
It makes no sense for a nurse on duty to wear large ear hoops. A flailing patient might rip them out.