I never saw anyone removed from the platform (except for one nutso whackjob who came in and tried to take over the meeting. He was escorted out, none too friendly like).
I can remember one time, when something like what OTWO experienced...where the chairman reminded the congregation to look up info from a newer magazine after the speaker gave wrong info. And it wasn't really all the speaker's fault...he was using a Society outline that had not been updated after a recent doctrinal change. (I mean, some of those outlines were as old as I was at the time...no way they could all be correct).
But there were many times where speakers went off on tangents and said things that were not officially sanctioned by the Society. It was usually older brothers who seemed to feel the need to give a tough-as-nails approach to some of the more disciplinary talks. Maybe they were counseled later in private, but I doubt it...the next time they gave a talk, it was more of the same.