My freashman year our guard had these tire-like props that they rolled around the field. Unfortunately they didn't know their charts very well, so when our directors decided to start in the middle of a chunk of music, the guard didn't know where to put the props. One ended up 5 yards off the mark, right where the tenor saxes and trombones were supposed to go on the next chart...
So the first person sat on it, but didn't have time to shout "drill" before the next person came and sat on him. The pattern continued for the entire chart. We had like 8 people piled up at the end. The trombone leader was sooooo mad. She went off and cussed out the guard.
Luckily, no instruments were damaged...oh, and nobody was hurt.