John Milius developed the idea of adapting Joseph Conrad's Heart of Darkness to a Vietnam War setting after his USC screenwriting professor challenged the class by saying no screenwriter had ever successfully adapted the novella.

The film's title was inspired by a hippie button badge from the 1960s reading 'Nirvana Now'.

George Lucas was originally set to direct the film in cinéma vérité style using 16mm cameras and real soldiers while the Vietnam War was still ongoing, but the project was shelved when he became busy with American Graffiti and Star Wars.

Steve McQueen, Al Pacino, Robert Redford, James Caan, Jack Nicholson, Robert De Niro and Clint Eastwood all turned down or were considered for the role of Willard before Martin Sheen was cast.

Harvey Keitel was originally cast as Willard and even signed a seven-year deal, but Coppola replaced him with Martin Sheen just weeks into shooting because he felt Keitel couldn't play the character as a passive onlooker.

Orson Welles and Lee Marvin both turned down the role of Colonel Kurtz before Marlon Brando was cast for a fee of $2 million plus a percentage of the gross, ultimately earning him around $9 million.

Laurence Fishburne was only 14 years old when filming began, having lied about his age to get the role of Mr. Clean; by the time the film was released three years later, he was 18.

Harrison Ford's character Colonel Lucas was named after George Lucas, while G. D. Spradlin's character General Corman was named after Roger Corman, who gave Coppola his first directing job.

Typhoon Olga destroyed 40 to 80 percent of the film's sets in May 1976, shutting down production for weeks and forcing much of the cast and crew to return to the United States.

Martin Sheen suffered a near-fatal heart attack on set at age 36 and crawled a quarter of a mile to get help; to keep the production's financiers from panicking, he claimed he had suffered heat stroke instead.

The opening scene of Willard getting drunk and punching a mirror in his hotel room was filmed on Martin Sheen's actual birthday while he was genuinely intoxicated; the mirror was real, not a prop, and he badly cut his hand but insisted on continuing the scene.

Marlon Brando arrived on set severely overweight and unprepared, forcing Coppola to disguise this by dressing him in black, filming mostly his face, and using a taller stand-in actor for other shots.

Principal photography, originally planned for five months, stretched to 238 days over more than a year due to the accumulating problems.

Real human corpses were purchased for the film from a man who turned out to be a grave robber; police became involved and the bodies were confiscated, forcing the production to use extras posing as corpses instead.

A water buffalo was actually slaughtered on camera by a local Ifugao tribe for the ritual sacrifice scene, leading the American Humane Association to give the film an 'unacceptable' rating since animal cruelty laws were not enforced in the Philippines.

Dennis Hopper and Marlon Brando did not get along during filming, and Brando refused to be on set at the same time as Hopper.

Japanese composer Isao Tomita was originally signed to score the film with an electronic sound inspired by his adaptation of Holst's The Planets, and even traveled to the Philippines with the crew, but label contracts ultimately prevented his involvement.

Sound designer Walter Murch had to fabricate the jungle ambience and helicopter sounds almost entirely in post-production because the recordings brought back from the Philippines were inadequate, and he pioneered an early 5.1-style surround mix for the film's 70mm release.

Colonel Kurtz recites T. S. Eliot's poem 'The Hollow Men' before dying, and two books seen on his desk, From Ritual to Romance and The Golden Bough, were the same sources Eliot cited as inspiration for that poem.

Dennis Hopper's photojournalist character quotes T. S. Eliot's 'The Love Song of J. Alfred Prufrock' and paraphrases the ending of 'The Hollow Men' ('not with a bang, but with a whimper') to Willard.

Apocalypse Now premiered as an unfinished work in progress at the 1979 Cannes Film Festival, the first such work-in-progress screening ever shown in competition, and went on to win the Palme d'Or.

The film's budget doubled to over $25 million and Coppola personally guaranteed a loan from United Artists, putting up his car, house, and profits from The Godfather as collateral to finish the film.