I'll play on this one... Starting this year and going backwards
In Madison's show, after a drum feature, the drum judge gets trapped in front on one of the hornline members, and the kid can't make his spot
End of Bluecoats' show, tenor drummer loses ENTIRE set of tenors on last hits. You can see him do the last hits, then it just tumbles off. ( Easy to see on high-cam, little harder to catch on multi-cam)
Also, beginning of Bluecoats' show, when the announcer points at the champion, drags his foot through the turf, and launches a wave of the black turf- buddies in the air (Not sure that's what the technical term is, but we always called them turf-buddies)
Phantom's show, the mellophone soloist jumps out of the drill just before the running section in the opener, then jumps back in at the beginning of the ballad
Going back a couple of years, in 2005, Quarterfinals, but during Cadet's show, during the drumspeak, the pit guy who starts it has his baldric and mirror come loose, so it's just hanging off his jacket at the end of the feature
In 2002, Cavie's show, when their doing the counting in the rhythm section, their counting by pressing down and releasing their valves, not good for the horns, but it worked
2000, there's an extra set of tenors out for the line to do their drum solo on
Way back to 1991, at the end of Phantom's show, when some of the members throw off their helmets, one of the trumpet players throws his horn away, you can see it on the right side of the screen on the video...