You could disable the clutch then you would have the real chain but it would not move and you could run the engine if you wanted to.
Universal Studios Halloween Horror Nights use real chainsaws (no chains). So, I guess if they do it, then it should be ok.I find this quite interesting. For the people that use real chainsaws, do you ever have people get upset about it? It seems to me like one level down from scaring people with a real gun that has had its bullets removed.