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10+ 'The Hangover' Behind The Scenes Secrets Fans Didn't Know

Once in a generation, a new kind of comedy comes along and completely blows the doors off of everything that's ever come before. For my generation, that movie was The Hangover.

As unbelievable as it seems, the film just recently celebrated its 10-year anniversary. Raise a glass and check out these 10+ The Hangover behind-the-scenes secrets that fans didn't know!

1. Zach Galifianakis was reluctant to meet Todd Phillips at first.

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Zach was in Canada at the time and was very hesitant to hop on a plane in order to audition.

By his own admission, auditioning isn't one of his strengths.

2. The cast could've looked incredibly different.

Several actors were considered for the film.

At one point, Jonah Hill was being considered for Zach Galifianakis' role. Jake Gyllenhaal as well as Thomas Haden Church were also possibilities at one time.

3. Contrary to popular belief, Lindsay Lohan didn't pass on the script.

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For a while, people were slamming Lindsay pretty hard in the press and on social media for allegedly not having the foresight to see what a successful venture The Hangover would be.

According to Todd Phillips, Lindsay loved the script. They just felt she was too young for the role.

4. Ed Helms was filming *The Hangover* and *The Office* simultaneously!

Ed had to work with showrunner Greg Daniels to work around his shooting schedule at Dunder Mifflin.

He was responsible for chartering and paying for his own flights. Oftentimes, Helms wouldn't even have time to sleep!

5. Todd Phillips discovered Ken Jeong for the first time on YouTube.

Todd watched Ken's video with Mike O'Connell on Funny Or Die and knew that he had to bring Ken in for an audition. During the audition, Ken won the room over by going completely and totally insane.

One person even said he sounded like the Tasmanian Devil!

6. Ed Helms really is missing a tooth.

Ed wears a dental implant. As odd as it might sound, his front tooth never developed!

He removed the implant for filming and then had it put back in place once things on set had wrapped.

Since Ed was still filming *The Office*, he had an oral prosthetic made in secret.

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In an interview with The Hollywood Reporter, Ed said:

"So I would show up to work on The Office with this appliance in my mouth, and it really affected my speech. If you watch those episodes, I sound drunk."

7. Some of the film's most memorable lines were totally ad-libbed between scenes!

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Ken Jeong gives all credit to Todd Phillips. According to him, Todd was constantly throwing one-liners his way — even in between takes!

The most memorable of which has to be"Tootaloo, mother[expletive]!"

In fact, Bradley Cooper dished to Collider about the freedom that they had on set.

"We use the script as a template. That’s the way it was on Wedding Crashers, too. If you cast it well enough, the situation is going to give itself to improvisation. The action causes dialogue," he said.

8. Ken Jeong was dealing with a family crisis while filming.

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Ken and his wife received the horrible news that she'd been diagnosed with breast cancer. It's part of why Ken became so unhinged through the character.

The only two people who had any idea were Bradley Cooper and Todd Phillips.

9. Todd Phillips created it all.

Before Todd found the script, the characters were incredibly different. There was no Mr. Chow, no cop car, absolutely no mention of a baby, and, most important of all, no Mike Tyson.

On behalf of fans of the film everywhere — thank you, Todd.

"No Tyson, baby or tiger. And there was no cop car. [Co-writer] Jeremy Garelick and I sat down in my house and just started writing. We kind of went backward, like, what would be the craziest thing you could wake up to? A tiger?"

"Well, why would a tiger be there? Siegfried & Roy? Nah, that feels typical. Oh, you know what’s funny? Mike Tyson. I once read he has tigers," Phillips told The Hollywood Reporter.

10. Todd Phillips' assistant had a truly brilliant idea.

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His name was Jeremy Garelick and it was he who came up with the idea that the guys should find the camera at the end of the film.

Zach Galifianakis liked it so much, he offered to pay Jeremy $1000 so long as he promised to present the idea to Todd.

11. Former president Bill Clinton visited the set.

While the crew was on location filming The Hangover 2 in Thailand, Clinton supposedly stopped by.

Rumors began circulating that he'd make a cameo appearance but according to Ed Helms, it was never meant to be.

12. Some of the jokes were polarizing.

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Todd Phillips was trying to walk the line between being bold and being offensive.

The jokes with the baby tended to land on both sides of the fence — even among the cast members.

13. Mike Tyson was still fighting his inner demons while filming.

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Former heavyweight champion Mike Tyson has had a long and troublesome battle with substance abuse.

Unknown to director Todd Phillips, Mike was still in the thralls of addiction when filming began.

14. The nude scenes almost got production shut down!

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Supposedly it was Ken Jeong's idea to do his scenes naked and Todd Phillips thought it was hilarious!

The Las Vegas police, however, didn't share their sense of humor, and Phillips was forced to build a blackout wall.

15. They didn't actually trash a room at Caesar’s Palace.

Instead, they decorated their own stage to look basically exactly the same as a room at Caesar's Palace.

This was obviously for an authentic feel, which seems to have worked in their favor!

16. The real employees in the background.

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When the cop car parks in front of Caesar's Palace, you can see in the background that two employees are actually having an argument!

That was in no way scripted!

17. Zach Galifianakis says that his favorite memory during the first movie was during the "older gentleman scene."

"The most I’ve ever laughed in my life was the day we shot the first one, I don’t remember if you call, the older gentleman scene when we were in the hospital with him, and he’s nude. I got the giggles so badly, and so did he, and so did he," he told Collider.

"There was nothing but euphoria running through my body, how much I was laughing. I had to walk off the set I was laughing so hard. That was also the day the election came in 2008. That was a really happy day."

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"A day I will never forget because my body was just beaming with just happiness, because of the giggles from that day and then also what happened that night was a pretty special night."

18. Ed Helms admitted that the movie was extremely difficult to film.

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Because of all the action sequences, the roles were all very physically demanding of the actors.

But the chemistry between the cast made up for any inconvenience caused by the demanding action scenes.

Do you know any more interesting behind-the-scenes secrets about *The Hangover*?

If you do, let us know what they are down below in the comments section! If you don't, let us know what your favorite fact was!

We would love to hear from you!