You should also be aware of what plant life is around the space. While working in outdoor theatre one spring, my director and some of the cast found their way into some poison ivy and poison oak. They quickly realized what they had gotten into, so it wasn't as severe as it could have been (no hospitalization), but it was rather unpleasant. Calamine lotion/hydrocortizone cream seemed to do the trick in that instance.
We never had ducks or other wild life grace our stage and chase the actors, but we did have a frisbee land in the middle of the stage during a performance of The Winter's Tale. The theatre was quite close to a "hole" for my university's Ultimate Frisbee course and people would play through in the middle of performances. My particular favorite frisbee moment, though, was when they hit our lighting professor with the frisbee. He had quite an interesting confrontation with the frisbee team leader. The lighting crew and I almost died of laughter.