I've been watching older events lately (first 12 UFCs, WVT 1,2 etc) and was wondering how Oleg's fight with Alvarez went. I think this event is the only one in Full Contact Fighter's database to have a result listed as "fans rioted"!
Edit for my stupidity, thinking of the MARS event there!
Pentagon Combat was the event with the Renzo VS Eugenio Tadeau main event. There was a huge feud between Renzo's fans (jiu-jitsu) and Tadeau's friends/supporters (Luta-Livre). There was a bunch of fighting going on outside of the cage and one of Tadeau's supporters actually ended up stabbing Renzo in the back. All hell broke loose after that and there was a full-fledged riot. Obviously the fight ended up being canceled. Thankfully Renzo wasn't hurt too badly.
Also on the card Bustamante KO'd Bohlander with an up-kick from the ground (ala Renzo/Oleg)
"I think this event is the only one in Full Contact Fighter's database to have a result listed as "fans rioted"!"
That was back in '97 if I remember correctly. More recently the UA 2 (Ultimate Athlete) show ended up in a riot.