I was surprised when I read that Bernie's dead body was always a real person, either Terry Kiser or a stunt double, and they never used a dummy or mannequin. It says in "Trivia" that the stunt double bruised his ribs being dragged behind the boat running into the metal posts. They didn't need a real person to be doing that, did they?
Don't know if you're kidding or not :-P In the "trivia" section, it says ...
===== Terry Kiser (Bernie)'s stunt double suffered a few broken ribs during filming due to all the pitfalls and stunts of playing a dead man; most notably in the scene involving 'Bernie' being dragged around the surface of the lake, bumping into metal floating obstacles. =====
During that scene I was sure it was a dummy of some sort, possibly a beanbag chair, but it never crossed my mind it was a real person, because it seems like it didn't need to be. The body just flops around and bounces off the metal things. Did that need to be a real person?