10 Actors Who Didn't Know They Were Being Filmed For Movies

It's no secret that The Exorcist was one of the most infamously gruelling film shoots in Hollywood history, Oscar-nominated director William Friedkin putting his ensemble cast through near-literal hell in an attempt to create as authentically terrifying an experience as possible.

This extended to Friedkin even firing guns on set in order to produce genuinely startled reactions from the cast, resulting in actor Jason Miller - who played Father Damien Karras - verbally confronting the filmmaker for the extreme practise.

But Friedkin didn't only fire the gun during actors' takes - he even set the gun off between takes, all while the cast were unaware that the director was surreptitiously filming their reactions.

Many of these reportedly made it into the final cut of the film: the various jolting responses when Regan (Linda Blair) makes noises in her room are actually the result of a brilliant-but-unhinged filmmaker shooting off a real gun on set and legitimately scaring the hell out of his actors.

You certainly wouldn't - and shouldn't - get away with that one nowadays.