Worst thing I've ever seen is the range officer announce the beginning of a shooting period while people were down range, a little slow in checking their targets during the ceasefire. Luckily all the shooters saw what the range officer didn't and stayed behind the safety line until the range officer noticed about thirty seconds later. At least he said "sorry". I don't think the people downrange heard the end of the ceasefire being called, because they didn't run back or wave their hands around or anything.
about 5 years ago (i specify this b/c the place has greatly improved since), i was at American Shooting Centers in houston. had an RO do this while I was the one still at the target board, then upon my return to the line (made at a rather hasty run, due to hearing line called hot!!) he confronts ME for being ahead of the line when he called the line hot!!
for the record, i made a complaint and received a refund for my day, since considering what else i'd seen this particular RO do (ie spend 90% of his time with his back to the line, BSing with his buddy) i was rather fed up with the whole thing.
I have since been informed that ASC has performed a "cleasing" of their RO staff and that such incidents are a thing of the past. personally i haven't fired a shot there since. mainly b/c soon afterward my membership application for a more "local to me" club was approved.