How about radiation sickness?
I remember from a movie about the space program that the astronaut would die if he vomited in his helmet.
Considering the radiation exsposure to and from Mars as well as the exsposure on the surface what is the possibility of this happening during a Mars EVA?
One would hope that at least the astronaut would be able to get up without assistance if he fell down, and that it wouldn't get ripped by a sharp rock that he fell on.
One may recall the Apollo moon missions when they did some falling.
Perhaps a little too much frivolity?