10 Actors Who Had To Get Drunk To Shoot Their Movies
3. Martin Sheen - Apocalypse Now (1979)

The chaotic sixteen month shoot for Apocalypse Now took its toll on everyone involved. Director Francis Ford Coppola contemplated suicide and lost 100 pounds, whilst star Martin Sheen had a heart attack. I think after that kind of stress, anyone might turn to drinking.
The famous opening scene featuring Sheen's Captain Willard in a hotel room was unscripted. Instead, Sheen got drunk during the shoot and Coppola told the crew to film.
During the scene, a nearly-naked Sheen actually punched a mirror, cut himself when it shattered, started crying, and - whilst covered in his own blood - nearly attacked Coppola off-camera. Almost all of this ended up in the finished film.