When I used to go to the ice hockey matches in the USA, an announcement was read out before each match saying that since the pucks may leave the playing area and spectators could be struck, you should leave now if that causes you any concerns. AFAIK No one ever got sued - but I did see lotsa supporters get hit in the bonce and go out for medical attention. They usually came back looking like Terry Butcher.
You cannot limit liability for death or PI in either the UK or the US.
I should sue Steve Staunton. At Forest, years ago, I was sat with my mate just to the left of the goal and the lads were warming up for the game. Staunton hit a screamer, as he quite often did, but I was looking away at the time. I only turned to see what was going on as the ball struck me smack in the face, to a collective 'ooooooooo' from those around me, and much hilarity to my mate. Bastard.
I was stood behind the goal at The Dell when Neil Cox was warming up and he belted a ball towards me, I turned round with my hands in my pockets to see it flying towards me and hadn't time to raise my hands so headed it to great cheers. It brought tears to my eyes and i'm sure I saw stars, never turned my back on a game since.