It's been 20 years since indie film legends the Coen brothers released The Big Lebowski — a film that got a mediocre reception at the box office, but later achieved feverish cult status.

The story is one of mistaken identity, where a pot-smoking, bowling-loving, slacker dude named Jeff Lebowski (Jeff Bridges) — friends know him simply as "The Dude" — gets beaten and tangled in a kidnapping and extortion plot involving a millionaire and his wife.

Entire online communities have sprung up around the film, and its stars — among them John Goodman, Julianne Moore, Steve Buscemi and John Turturro — still have people come up to them quoting their favourite Lebowski lines. There's even a travelling Lebowski Fest that includes a screening of the film and a white Russian-fueled Lebowski-themed bowling party.

This week, The Big Lebowski turns 20, so here are 10 fascinating facts that you may not know about the legendary film.

Warning: film clips contain strong language, violence and suggestive scenes

The film was inspired by Raymond Chandler stories

The Big Lebowski was inspired by the detective fiction of Raymond Chandler, who penned The Big Sleep and Farewell, My Lovely, which became hit films. He also co-wrote the screenplay for Double Indemnity with Billy Wilder, which was nominated for an Oscar, as well as The Blue Dahlia, and he collaborated on the screenplay for Alfred Hitchcock's Strangers on a Train. "We wanted to do a Chandler kind of story – how it moves episodically, and deals with the characters trying to unravel a mystery. As well as having a hopelessly complex plot that's ultimately unimportant," said Joel Coen in an interview. "And there was something attractive about having the main character not be a private eye, but just some pothead intuitively figuring out the ins and outs of an elaborate intrigue," added Ethan. "And then there's Walter [John Goodman], whose instincts are always wrong."

The Dude is partially based on a real dude

The Coen brothers have said the film's central character, Los Angeles slacker Jeffrey "The Dude" Lebowski, is an amalgam of people they knew — but one of the biggest inspirations was American film producer and Vietnam War activist Jeff Dowd.

There's also a real Walter

John Goodman plays the tough-talking Vietnam-obsessed veteran Walter, a character loosely based on script editor Peter Exline whom the Coens met while making their film Blood Simple. They called him "Uncle Pete, the philosopher king of Hollywood." At one point, I couldn't go 10 minutes without mentioning Vietnam," admitted Exline. The Coens made one key change, however: Exline wasn't a bowler; he played softball.

Julianne Moore's accent is not an accent

Actress Julianne Moore plays Maude, the daughter of the millionaire Jeffrey Lebowski — the actual target of the kidnapping and extortion attempt — and when she first read the script, Moore loved the language. Next she had to define a distinct voice for Maude, who creates "vaginal" art. "The first time I did it, Ethan said to me, 'I love that boarding-school accent you do.' I told him it wasn't an accent, it was an affectation," remembered Moore. "And that was the character, to me." Her character eventually became pregnant with a "little Lebowski."

Jeff Bridges had a key question before shooting each scene

The Coen brothers say that, like The Dude he played, Bridges was very low-key and low-maintenance — but there was one key piece of information he wanted to know before shooting each scene. "At the start of shooting every scene, he'd walk up to one or the other of us and ask if we figured the dude burned one on the way over," says Ethan, referring to The Dude's prolific marijuana habit. "So thinking about it, usually we'd say, 'Yeah, he probably burned one on the way over,' and Jeff would go over in the corner, rub his knuckles in his eyes to turn them red, and do the scene. And that was kind of the extent of what you had to do to direct Jeff."

It was set during Gulf War — but not because of politics

The Big Lebowski is set during the Gulf War of the early 1990s, but the Coen brothers weren't out to make a strong political statement. Rather, they needed something that Walter — The Dude's right-wing, tough-talking sidekick — could be upset about. "Setting the film during the Gulf War was an opportunity to have Walter gas about something," said Ethan in an interview. "And it's more attractive to make something time specific than just present day." In one of the film's dream sequences, former Iraqi president Saddam Hussein is even seen working at a bowling alley and handing The Dude a pair of bowling shoes.

The Dude reminded Jeff Bridges of himself in the 1960s — and he had the wardrobe to match

Jeff Bridges is a veteran actor with a lengthy list of accomplishments, but he says that, back in the '60s, he wasn't unlike The Dude. "It reminded me a lot of myself back in those days. I smoked my share of pot and all that, and the long hair," he told Rolling Stone, adding that he taps into elements of himself when he's stepping into a character. "I do that on an emotional level, but also on a physical level. My looks and my wardrobe are very important. I kind of work on the exterior and the interior at the same time. They kind of inform each other. So we went up to my closet to see my clothes, kind of match The Dude. And we just found all kinds of stuff. Those jelly sandals, some T-shirts that I had."

The acting looks like it could have been improvised, but it wasn't

The acting is so natural, and the comedic timing so spot-on, many assume that at least some of the scenes had to be improvised – but actor John Goodman says no.

"I had so many people ask me if it was improvised. I'm not that smart," he said with a laugh. "I'm not that good, but we got lucky and rehearsed for a couple of weeks before we started shooting. That's why that looks so good, like we're improvising."

Goodman also says that, because the characters were so clearly drawn, it made their job easy. "What they had on the page was so fully realized that it didn't matter who these guys were, it didn't matter if they existed. All that mattered was what was spelled out on the page, and it was so vivid in my mind," he remembered. "Everything was spelled out for you. It's almost idiot-proof. Almost, I say."

A professional bowler taught the actors how to bowl

The central characters in The Big Lebowski are all bowling buddies, and to make sure their alley moves looked authentic, the actors were trained by pro bowler Barry Asher. "I can remember John [Turturro] and I and Buscemi, we took bowling lessons from this guy," remembered Bridges in an interview. "He was a champion, one of the best bowlers in the world." When Bridges asked him how he got in the zone before each shot, Asher went into a long story about how he would sometimes stand for 10 minutes before throwing the ball. "So he's waiting for his mind to get in the right place before he winds up, and sometimes his mind wouldn't be there, and so he kept waiting and doing different things, ticks and twitches, to get there. And finally he had to actually go to a doctor and work on it. 'Well how do you do it now?'" asked Bridges. Asher's answer? "'Now I just get up and throw the f--king ball.'"

When they wrote the script, the Coen brothers imagined The Dude and Walter as a grumpy married couple

They're the best of friends, but The Dude and Walter disagree constantly — and their bickering makes for some of the film's most entertaining scenes. But it turns out that, during the writing process, the Coen brothers didn't look at them as buddies; they modelled them after a married couple. "The characters were conceived as being partners in a dysfunctional marriage," said Ethan in an interview. "We designed them so they would constantly be pushing each other's buttons, you know, getting on each other's nerves — and yet still at a certain level really liking each other."

The Dude appears in every single scene

There isn't a single scene in The Big Lebowski where The Dude doesn't appear. Dude, does that, like, blow your mind?

John Turturro is making a film based on Jesus Quintana

The Coen Brothers have repeatedly vowed they will never make a sequel, despite the pleadings of Big Lebowski fans. However, they did give permission for actor John Turturro, who plays pederast and star bowler Jesus Quintana, to write and direct a film around his character. (The Coen Brothers were not involved, and it does not include any other Big Lebowski characters.) Going Places doesn't yet have a release date, but the film features Susan Sarandon, who plays a criminal freshly released from prison, as well as Bobby Cannavale, who competes with Quintana for the affections of a woman played by Audrey Tautou. It was reportedly inspired by Bertrand Blier's 1974 film Les Valseuses, and originally titled 100 Minutes with Jesus.

So what does it all mean? Maybe nothing.

Countless Lebowski fans have hypothesized and debated the possible meanings that underlie the film, but Bridges says the Stranger sums it up with his last speech — watch is below. "You know, 'I hope you had a good time, it was funny.' So that was one message, that life is funny. You can find the humour in it," Bridges said. "Bernie Glassman, who is a Zen master, said to me one day, 'You realize that many people in the Buddhist community look at The Dude as a Zen master?' And I said, 'You've gotta be kidding me.'"