Many people have had an eventful night in Las Vegas. They don’t always turn out ideally. The Hangover took that concept and took it to the next level. In doing so, the film made movie stars of its cast and helped define the comedy blockbuster for the era. Here are 20 facts you might not know about The Hangover. Or maybe you knew them, but you’re dealing with a hazy memory at the moment.

The decadence of The Hangover came from a real place. Producer Chris Bender told a tale of his friend Tripp Vinson, a movie producer. Vinson apparently went missing from his own bachelor party in Las Vegas, only to regain coherence in a strip club, at which point he was told he had a massive bill to pay.

The screenwriting duo of Jon Lucas and Scott Moore crafted the script based on Bender’s story and then sold it to Warner Bros. for a cool $2 million. After Todd Phillips came on board to direct, he and screenwriter Jeremy Garelick did a rewrite, which added Mike Tyson, his tiger, and the baby. However, the WGA gave Lucas and Moore sole screenwriting credit in arbitration.

Tyson was written into the script, but when approached, he declined. Then, he found out that Phillips had directed Old School, and he enjoyed that movie. That got Tyson to sign on for his cameo. Weirdly, Tyson has said that working on The Hangover set him on “a good path to a healthy life.”

Before Heather Graham signed on to play Jade, the closest thing to a “good role” for a woman in the movie, Lindsay Lohan was apparently in talks for the role. However, Phillips decided she was too young for the part.

Phillips plays a small role in his own film. He performs the role of Mr. Creepy, the guy in the elevator. Skateboarder Mike Vallely also has a small role as Neeco.

Phillips and the crew went to the actual Caesars Palace in Las Vegas to shoot the film. They used a lot of real locations in the hotel and casino, including shooting on its roof. That said, the damaged suite in the movie is not a real hotel room in Caesars Palace but a set on a soundstage.

Ed Helms, who plays Stu, has called The Hangover the most physically demanding movie he’s ever shot. He didn’t really lose his tooth, though. Helms never had an incisor grow in after losing his baby tooth, and he had his implant removed to shoot the movie.

Phillips wanted to use a real Taser in the movie. He was in the process of trying to convince the actors to get on board when the Warner Bros. legal team stepped in and put a stop to this loony idea.

Ken Jeong, a trained medical doctor, got the green light from his wife to appear nudė in the movie. He and Bradley Cooper improvised the scene where Jeong jumps on Cooper’s neck while naked. On the other hand, a prosthesis was used for the photo in the final slide show of Zack Galifianakis’ character in the elevator. And yet, Galifianakis hated shooting that, saying, “I was extremely embarrassed. I really didn't even want it in there. I offered Todd's assistant a lot of money to convince him to take it out of the movie. I did. But it made it in there.”

People do all sorts of things when acting that they don’t do in real life. We’re pretty sure Daniel Day-Lewis has never beaten a man to death with a bowling pin, for example. On a smaller scale, Cooper quit drinking when he was 29, so by the time he starred in The Hangover, the idea of getting blackout drunk was long behind him.

The Daily Show with Jon Stewart has long been a jumping-off point for future comedy stars. The Hangover is a good example of that. The movie has four former Daily Show correspondents: Helms, Rachael Harris, Rob Riggle, and Matt Walsh.

Helms and Galifianakis have musical chops. The former is the most famous banjo-playing comedic actor on this side of Steve Martin, and the latter used to play piano in his standup act. Their songs in the film, “Stu’s Song” and “Three Best Friends,” were improvised.

If you have heard of The Dan Band, you probably owe that to Phillips. The comedy band fronted by Dan Finnerty is known for its vulgarity-infused cover songs. They previously appeared in Phillips’ “Old School” and “Starsky and Hutch,” and they feature in The Hangover as well, adding a cover of 50 Cent’s “Candy Shop” to the soundtrack.

Apparently, some parents of younger children approached Galifianakis to tell him that their kids loved The Hangover. In turn, they would find themselves yelled at by the actor for letting their kids see the movie. Given the hard-R nature of the film, that's a reasonable reaction from the movie’s star.

Warner Bros. had hopes for their R-rated comedy, even if it was a December release. The expectation was it would probably finish third at the box office behind Up in its second weekend and fellow new comedy Land of the Lost. When the latter flopped, it opened the door for The Hangover. The movie finished atop the domestic box office in its first weekend and held onto that for its second weekend.

Made from a budget of $35 million, box-office success would have been easy enough to come by. The Hangover exceeded all expectations. When all was said and done, it made $469.3 million worldwide. Domestically, it finished as the ninth-highest-grossing movie of 2009 and set a new record as the highest-grossing R-rated comedy, besting Beverly Hills Cop.

Phillips bet on himself with The Hangover. To get a little extra money for the film, he waived his salary in exchange for a percentage of the profits. It worked out big time. Reportedly, when all was said and done, Phillips made $50 million off of The Hangover. He has called the film “my Star Wars,” a reference to George Lucas getting profit participation in that movie.

The Oscars had no interest in The Hangover, but the Golden Globes did. They gave the movie Best Picture in the Musical or Comedy category. Additionally, AFI named it one of the top 10 movies of the year.

Vegas is a tourist town, and it has not exactly shy about publicity or appealing to the masses. The Hangover ratcheted up interest in the longtime destination city, especially among guys who wanted to have a Hangover weekend for themselves (for whatever reason). Caesars Palace started selling Hangover-related souvenirs, and branded slot machines began to pop up around the city.

The massive success of The Hangover led to The Hangover Part II, which made a staggering $586.8 million to break the first film’s record for an R-rated comedy. This led to a third film. In an interesting turn, it was a dark film that effectively antagonized the fans of the first two movies. It only has a 20 percent rating on Rotten Tomatoes and earned $362 million worldwide. This ended the series, seemingly to the relief of the film’s three stars.

Chris Morgan is a sports and pop culture writer and the author of the books The Comic Galaxy of Mystery Science Theater 3000 and The Ash Heap of History. You can follow him on Twitter @ChrisXMorgan.

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