Have you ever started filming a movie you thought was a comedy, but it was actually a horror film? Probably not because, chances are, you're not a famous actor (but if it is you, Mr. Murray, humanity doesn't deserve you). But believe it or not, this kind of stuff actually does happen to movie stars. Actors who thought they were making different films (or at least, different kinds of films) are, well, people in Stephen King movies, mostly. And then there are actors whose roles were much different than they thought they'd be, including such big names as Charlton Heston, Halle Berry, and the whole cast of The Usual Suspects.
It's surprising, but it happens more than you might think. Sure, actors could pay attention to what they're doing, or give a flying muffin about more than just a paycheck, but then we wouldn't have these hilarious stories. Here are some knee-slapping instances of actors coming out the back end of a film with no idea what the world was about to see.