In the scene with the man making the movie when they attack the beach, the man shooting the movie saying "Don't look at the camera" is actually Francis Ford Coppola.

Laurence Fishburne (who played Tyrone "Clean" Miller) lied about his age to get cast. He was 14 when production started, but told director Francis Ford Coppola that he was 17.

Martin Sheen suffered a heart attack while filming in 1976. Sheen's brother, Joe Estevez, doubled in, as well as providing Willard's voice-over narrations.

Harvey Keitel was originally cast as Captain Willard. Two weeks into filming, director Francis Ford Coppola felt Keitel wasn't taking the role seriously enough, so he fired him and reshot scenes with Martin Sheen as his replacement.

Principal photography took 274 days. This is the same amount of time it took Peter Jackson to complete filming for all three "Lord of the Rings" films.

Martin Sheen actually was intoxicated when he filmed the scene where Willard is drunk in his hotel room. He punched the mirror, which was real glass, and actually did cut his hand, as shown in the film.

This film took so long to make critics jokingly dubbed it "Apocalypse Later".

Marlon Brando (Colonel Walter E. Kurtz) showed up to the set 50 pounds overweight and admitted that he had not even read the script yet. Brando demanded that he be shot only in shadow and that his scenes be almost entirely improvised. He said he did this because he didn't want to work as hard. Francis Ford Coppola has not worked with Brando (who has a notorious reputation for being a difficult actor to work with) since then.

The scene where Colonel Kilgore offers his canteen to the wounded Vietcong is based on a real incident. The army officer really did say, "Any man brave enough to fight with his guts strapped to him can drink from my canteen any day". (From Hearts of Darkness: A Filmmaker's Apocalypse).