I saw someone forcibly removed from the hall once.
But I know of an incident, that I was not at but heard about the next day as did everyone else in the hall thanks to gossipy elders and their wives...
A heavy duty Judicial Committee meeting was being held at the hall due to some adulterous activity that had come to light. A MS had been having an affair with a sister in the hall. The sister's husband was not a JW.
During the JC meeting where the MS was being "tried", the sister's husband broke into the meeting and proceeded to beat the shit out of the brother who had been messin' round with his wife. The elders lifted not one pinky to help. As one was quoted later, "he should've thought about the consequenes of his actions..."
The next few meetings, including the announcement of his DFing, the ex-MS sported a swollen nose and a black eye.