I've seen people get hit in the head with cars(mostly slashes). Its not fun at all. There is an older guy at our track that got hit in the head with a T4 that had the one long body clip going across to both body posts and the end of the clip caught the guys head and he ended up needing to get stitched up. My local rack doesn't let just anyone marshall anymore. you need to be a racer(no fans), and above a certain age. I've personally had my finger mangles when a 8 yr old kid didn;t have a gear over on his slash and when I went to marshall him he hit the throttle.
Now if they hit the throttle I just watch them and wait until they are done

. I think people need to see where they are at, where the cars are coming from, and not stand by the jumps. Some common sense will save you in the medical bills.