I was one of those Thanksgiving Turkey Trot 5 milers. They have a problem every year with the lineup. All the 45:00 5 milers think they should line up ahead of the 25:00 guys, and when the gun fires, it's a disaster. The race director is thankful is they manage to start less than 50 meters past the starting line since everyone inches their way up.
Anyway, this time they began and I was towards the front. There is a veritable stampede of pleasantly overnourished joggers and one serious racer went down and was nearly trampled. Someone stopped to help him up and there was a huge mess as things got backed up. It wouldn't have been funny if the guy was hurt but he was alright.
The other was at the same race another year. A guy was doing the race on crutches. No joke. He was literally propelling himself along with a bad leg and one crutch at about 6 minute mile pace. I've never seen anything like it. Eventually I passed him, but it would have been embarassing to be beaten by an injured dude using crutches.