I'm curious if their death waiver has ever been tested in court? One law blog says they're not aware of any lawsuits and the waiver appears to be "legally sound or no one has tried to challenge it."
This picture was on their Facebook wall. It's amusing to me because several months ago TM had job postings for 3 attorney positions on their website. I checked again after they posted this picture and it appears they now have at least 3 attorneys.
I am aware of one death (a friend of a friend) where the family (and doctor I would assume) speculated that the death was the result of a Tough Mudder race. He finished a Tough Mudder race and died a few weeks later. The cause of death was due to the inhalation of certain mold spores commonly found on soil with a lot of moisture...basically places where Tough Mudder races are held. The takeaway was, if you have weird respiratory issues after a TM race, make sure you tell your doctor you did one of these races so they can treat you for those types of molds.
Given the popularity of these races and the number of people that might want to think twice before trying one but didn't, it's likely only a matter of time before it's tested in court.