I think the risk of getting hurt at MX and Hare Scrambles are pretty simular. I've been hurt doing both. but when engageing in any activity there is a risk. Just think you don't need to worry about getting hurt and just have fun. When it's no fun any more, don't do it.

MX:
Broken Ankle
Torn ACL

Off road/ hare scrambles:
Pulled back ligaments
Broken Toe
Broken Arm
Ruptured stomack
2 concousions
multiple stabbings by enviornmental objects. ie cati, trees etc

Skateboards:
broken arm
broken Tib fib
road rash on back
broken nose.

MTB:
Broken clavical
Broken Hand
broken arm
pealed off skin on shins
concussion.

Rugby:
4 concussions
Torn ACL
broken fingers
broken nose
sprained ankles.

Being at the wrong place at the wrong time:
Broken Toe and rippend off toe nail -drunk college
slipped disk - work
concussion - car accident
broken nose - car accident
whiplash - car accident
etc. etc. etc.