As per the thread title, in terms of train wreck 'moments', rather than the whole gigs, I'm sure we've all had plenty of those?
At various gigs I have had to, and other band members have had to:
Catch a falling PA speaker that a (drunk) punter has crashed into.
Do some tap dancing because a (drunk) punter stepped on one or more FX pedals.
Deal with the (drunk) punter who tries to take a microphone.
Avoid the (drunk) and usually (always) female punter who is trying to steal my hat while I'm playing.
Plenty more...