I nailed a kid once on accident when I was running down the side of the field while playing rugby. I didn't even really know that I had ran him over till someone pointed it out to me. Accidents in sports of this type are more common than most people suspect. I remember a guy getting his jaw broken after getting rocked while watching a match from the sidelines as well.
Good ending on this incident though:
http://http://niceone.aol.com/2008/11/26/wide-receiver-scores-extra-points/?icid=aimDBDL1_link1-a
