Now back in theaters for its 40th anniversary "Apocalypse Now," is both one of Francis Ford Coppola's most celebrated films and one of the most notoriously troubled productions in history.

It was released on August 19, 1979, more than three years after Coppola began shooting. What went wrong?

As Coppola said at Cannes, making the film was just like the U.S in Vietnam. "We were in the jungle, there were too many of us, we had access to too much money, too much equipment, and little by little we went insane."

Here's some of what went down in the Philippine jungle:

1. Original star Harvey Keitel was fired after six weeks

Coppola hired Harvey Keitel based on his work in Martin Scorsese's "Mean Streets." After he watched the first week’s footage, Coppola decided to fire him, yielding the first dramatic headlines of the production: "Coppola loses his beard, 38 lbs and Star Keitel.' He was replaced by Martin Sheen. The only footage of Keitel that made it into the film is a shot of him from the back on the boat.

2. Martin Sheen was really drunk, and really bleeding, during his Saigon Hotel scene

In this excerpt from Eleanor Coppola's Emmy-winning documentary "Hearts of Darkness: A Filmmaker's Apocalypse," Sheen recalls shooting the scene where Willard smashes a mirror in his hotel room: " I was so drunk, I couldn’t stand up, frankly. I was so intoxicated, I didn’t realize how close to the mirror I was.” Despite bleeding profusely, Sheen insisted on continuing filming.  Eleanor adds that Marty was so unpredictable at that point, she thought he might lunge at the camera or attack Francis,.

3. Sheen had a heart attack and received the last rites

You've surely heard Sheen had a heart attack during production. What you might know is that he crawled out of his room at 2 a.m. and a quarter of a mile down the local highway before finding help. "He had suffered a serious heart attack and even received last rites from a priest who did not speak English," Eleanor Coppola says in "Hearts of Darkness." He took six weeks off and, not wanting to halt the already over-budget production, said that he had suffered from heat stroke.

4. Coppola didn't want word of Sheen's heart attack to get out

In "Hearts of Darkness, co-producer Tom Sternberg recalls he got a phone call from his secretary, who said “Marty’s had a heart attack and Francis doesn’t want to admit it." Coppola is later heard on tape saying, “If Marty dies, I want to hear everything is okay, until I say, 'Marty is dead.'"

5. Coppola mortgaged his house to finish the film

Coppola had financed the movie himself, thanks to his success with the "Godfather" films, but had already blown the $13 budget. To finish the movie, he mortgaged his considerable estate to secure additional money from United Artists. If the film hadn't earned at least $40 million, he would have lost it all. ("Apocalypse Now" went on to earn more than $78 million during its initial release, as well as 2 Oscars, and shared top prize at the Cannes Film Fest.)

7. Filming took place in the middle of a real war

Coppola made a deal with Philippine President Ferdinand Marcos to lease his helicopters — if they weren’t needed in actual fighting. (The U.S. military refused to participate in a film about the Vietnam war).  Because of the Civil War in the south, every day the Philippine government sent different pilots, who hadn’t participated in the rehearsals. Even worse,  in the middle of a complicated shot, the helicopters would often be called away to fight the rebels in the nearby hills.

8. A typhoon destroyed several sets

In May 1976, the Philippines was hit by a typhoon that killed 374 people and destroyed many of the movie's sets, including the Playboy Bunny set. The production closed down for 2 months to rebuild.

9. Coppola insisted on serving up a real French feast during the French Plantation scene

Before filming the French Plantation scene (which was cut for theatrical release but added back for "Apocalypse Now: Redux"), Coppola insisted that the white wine  be served ice cold and red wine should be served at 58 degrees. "I want the French to say, 'My God, how did they do that?,'" he says in "Hearts of Darkness." He made the decision to cut the entire sequence right after shooting it.

10. Marlon Brando demanded a $1 million down payment -- then almost didn't show

After Al Pacino turned down the part, another "Godfather" star, Marlon Brando, agreed to play Willard's target, the mysterious Col. Kurtz. He was supposed to lose weight for the role and read the novel "Heart of Darkness" that inspired the movie. He did neither. Instead he turned up 88 lbs overweight and completely unprepared. At one point, he threatened to take Coppola's initial $1 million without ever setting foot on set.

(A Brando biographer disputes that the actor was unprepared and says that not only did the two communicate extensively about the character beforehand, Coppola was simply looking for a scapegoat at that point in filming.)

11. Brando spent his first days on set improvising his character

According to "Hearts of Darkness," Coppola spent several days of the actor's precious time in improvisation before shooting a single scene. He figured that getting Brando to start improvising (which he did throughout his scenes) was better than trying to get him to memorize a script. (On the "The Godfather," cue cards were pasted all over the set because Brando often forget his lines.)

12. Real people played the severed heads -- through 38 takes

The people who were playing the severed heads sat in their boxes in the ground from 8 in the morning until 6 at night: Coppola did 38 takes. Between takes, they were covered with umbrellas to shield them from the hot sun.

13. People were really doing drugs on set

Sam Bottoms, who plays surfing soldier Lance, admitted he dropped acid during filming, but not during the Do Long Bridge sequence where his character is tripping. "I was doing speed then. We were working lots of nights and I wanted a speedy sort of edge. We were bad, we were just bad boys," he says in "Hearts of Darkness."

14. Dennis Hopper and Marlon Brando hated each other

Dennis Hopper, who admits in "Hearts of Darkness" that his career was at a low point and he was happy to go anywhere and make any movie at the time, was only cast 2 weeks before his scenes. Coppola was afraid to put “crazy” Hopper with Marlon Brando in a scene and he was right: The two hated each other. They had to shoot their shared scenes in separate shots. When Kurtz throws the book at Hopper's character and calls him a "mutt," that was probably one of Brando's many improvisations.

15. Coppola contemplated suicide or injury to get out of finishing the film

As he says at one point in "Hearts of Darkness," "I’m going to be bankrupt anyway. I’m thinking of shooting myself." He was so desperate to get off the film, he contemplated what kind of sicknesses he could get or how he could maybe injure himself by falling off a platform, so he could have "a graceful way out."

16. Coppola convinced John Milius the film was going to win a Nobel Prize

John Milius, who wrote the original script, recalls that he was called in to put the script back together after Coppola's extensive revisions.  He was told by the frustrated crew to talk some sense into Coppola. Instead, Francis had him convinced this was the first film that would win the Nobel Prize.