What's with all the Larp movies lately?

David is correct. Property owners can be held liable for injury occuring on their property especially if there exists implied and/or express consent. I wouldn't try sparring at the movie theater. Stick with just costumes and fliers. (And get permission for the fliers, lots of places have rules against solictation) It wouldn't serve any good purpose to get kicked out of the movie theater.

If you wanted to arrange from some sparring on private property elsewhere at a later date, that would be a whole different matter (and a permission and liability question for whoever's place you held it at).