My worst/scariest fall was probably on bars. I peeled out of my giant early and ended up doing sort of a layout flyaway, but I managed to nail my feet on the bar coming down, which 1) hit a blood vessel or something on one of my feet which resulted in this HUGE bloody looking/bruised bump, and 2) caused my motion to stop so I came down on my head. Luckily no serious damage but the idea of a neck injury scared me to death.
I actually saw this very thing happen yesterday at our meet. My dd wanted to go watch the level 10s compete (had to watch her beloved Ms. Morgan) and one of the girls did this exact thing. It was sooo scary to see. The way she hit the mat and her body just crumpled on top of itself. She let out this blood curdling scream..that was match a split second later by her mother. There was a "team medic" in the building and he, our gym owner (we were host gym), and our HC, her HC went running over to her. Our L10 coach ran outside for a few seconds, only to be followed back in by 2 EMTs. I guess they had them outside on stand by for such an inccident. (im guessing this is normal, i know when i was a kid they were always at ball games too). It was scary scary scary to see.
She did an excelent routine, and it was during her dismount that this happened. She did three giants, then let go and was flipping around and the tops of both her feet hit the high bar and it just drove her head first into the mat. I mean it looked like she was shot out of a canon she changed direction so fast.
She was taken to the ER, and a couple hours later they announced that she was okay. But it had potential to be life altering