People can sue you no matter what is going on in your yard. Someone who trips coming up to your door Trick-or-Treating because they see that you have a ghost hang in the tree out front or someone who trips because they see a whole lot of tomb stones and stuff. It will not change the fact that they triped in your yard. The only thing that changes is the number of people coming into your yard and what you have there that could hurt them. MAKE IT SAFE and keep a eye on them so that they don't do something dumb. In two nights we are shooting for 400 to 500 people per night. So I am hiring a off duty cop to keep the peace. As for your insurance , they will tell not to have anyone at any time come into your yard for any reason. I bet you did not know this but, if someone comes into your yard to say read the meter or is making a delivery and they get hurt from something that you have control over like a tree root that is sticking up they can sue you but, thats why you have insurance. Good luck and am sue everything will be find, just make it safe don't give anyone a reason.