Can you imagine this switch in The Holiday? 

Seventeen years after the Christmas movie's release, Robert Downey Jr. and Jimmy Fallon revealed they both auditioned for the Nancy Meyers film starring Kate Winslet, Cameron Diaz, Jack Black and Jude Law.

"We both got called in just as seat fillers and we saw each other," the Iron Man star recalled on the July 16 episode of SiriusXM's The Howard Stern Show. "Jack Black is getting his part, and Jude Law is definitely getting my part. But she needed someone to read with the gals, and we're sitting there going, 'It's about to happen for us.'"

Downey was so confident he'd land Law's role (Graham, the brother to Diaz's Amanda) that he began perfecting—more so his description than ours—his British accent for his audition at New York's Carlyle hotel.

"I was like, 'I gotta have a better English accent than Jude Law at this point,'" he continued. "And Winslet said, 'That was the worst British accent I have ever heard.' And I was like, 'I'll check out now, but I'm taking the gummy bears from the mini bar.'"

Meanwhile, Fallon really wanted to nab the role of composer Miles, who Winslet's Iris falls for in the film.

"I said, 'If Jack Black says no to this movie, I'm so in,'" he shared. "'I'll do it for half his price.'"

Or offer his salary to Downey.

"By far, without a doubt, I'm sitting across from Robert Downey Jr., and I go, 'This is the best actor I've ever sat across and did a scene with in my entire life.' It was mind-blowing for me," Fallon remembered before joking, "and I quit the business. I never went back. That was the last time I auditioned for a role."

Thankfully, Downey wasn't so quick to give up, even though he too lost the gig. As he recalled, "Nancy said to me, she said to both of us at the same time, 'It's just—this was great. It's just not a perfect fit.'" 

For more secrets about The Holiday, keep reading.

1. Director Nancy Meyers wrote her leading ladies Iris and Amanda with Kate Winslet and Cameron Diaz in mind. 

"You know, I think a screenwriter would lie to you if they said, 'I don't think about anybody when I am writing,'" the famed scribe told ComingSoon.Net. "I can't imagine it, you know somebody has got to say it and do it. It's natural to start fantasizing about who is going to be in it."

2. To be fair, casting Winslet was pretty much a no-brainer. "If you're writing a 30-year-old woman in England you obviously think of Kate Winslet, she's just one of the great actresses," Meyers explained to ComingSoon.Net.

3. While Winslet was the inspiration for Iris, the Titanic star was convinced she was going to be fired from the movie. 

"I've never done a romantic comedy or something that is labelled as that before," Winslet explained to About.com in 2006. "I was so excited to do something new and also nervous you know? The worry of, 'Can I be funny?' It's a terrible thing to be concerned about. And Jude [Law] and I would speak on the telephone a lot before we started shooting. 'Oh my god, they're going to fire us! They're going to recast. What if we don't make them laugh?' You know, very nervous about the whole thing."

4. When it came to her California-based movie trailer editor who never cries, Diaz was an obvious choice for Meyers.

"Cameron is a great comedienne and I thought about this before I cast her and once I cast her she continued to thrill me in that area," Meyers said. "It's really hard I think to be that cute and sexy and that funny and that sort of girl-friendly. I am really only interested with women in my movies that are girl-friendly, I'm probably never going to work with those girls that only the guys like because I just don't get them. So Cameron's really a girl's girl and boys adore her obviously. She seemed absolutely the right choice for a California girl."

5. Though Jude Law made millions of movie-goers swoon as single dad Graham, he isn't what Meyers' initially had in mind for the part.

"Jude's character evolved more during the writing than the others," she admitted. "I sort of put him through some twists and turns that you don't expect. Then, when I was done, of course you think of Jude Law. He's so handsome and he's really such a terrific actor, but I wasn't immediately sure that he was going to fit into the genre and do this kind of work. So I met with him and we went through the script together and he just got it. You know, he just hasn't had a chance to do it before."

6. For Miles, Iris' love interest, Meyers wrote the role for Jack Black after seeing him in School of Rock, explaining to ComingSoon.net, "I just adored him, I thought he popped off the screen. He spoke to me as an audience member."

"When I was thinking of this movie I thought he was someone I would like to write a part for and I'm aware he's not Clark Gable, he's not tall dark and handsome, but he's adorable, he's lovable," she continued. "It's my way of saying this is the right kind of guy, this is what most guys look like if they're lucky, he's so adorable, and why not? Everybody has a heart and deserves to fall in love and he should get a great girl. So I fixed him up with Kate Winslet."

7. And it was being partnered with Winslet that ultimately got an unsure Black to sign on, with Meyers even trying to woo him over a pasta dinner. 

"Kate was incredible as I anticipated," Black told Coming Soon in 2006. "It was a huge reason why I wanted to do the movie. I was such a big fan of hers, I just love her work and her acting."

8. Miles and Iris' boob graze moment wasn't in the original script and was inspired by a real encounter between Black and Meyers.

"One day on the set he bumped into me and said, 'Oh, sorry about the boob graze,'" Meyers told Coming Soon. "I just laughed so hard because men bump into women all the time like that and act like they didn't do it, but he immediately said sorry about the boob graze so I wrote it into the next scene he did."

9. Winslet and Rufus Sewell, a.k.a. Iris' very awful ex-boyfriend Jasper, actually dated IRL in the early 1990s for a few months. But things weren't awkward on set.

"It was completely fine," Winslet told the Irish Examiner. "I hadn't seen him for a very long time but we'd remained friends. It was really not a big deal. I was thrilled he got the part."

10. Sure, Amanda's Los Angeles home is gorgeous, but Iris' cute country cottage was the real swoonworthy location among the crew. After initially finding a charming home, the producers decided to build their own so they could be closer to London.

The production team built Rosehill Cottage in only two weeks, with Meyers saying in a DVD feature, "We built that wall and we put in those trees. It really was just an empty field. It was a real tourist attraction while it was there." Unfortunately, the building was torn down after filming and all of the interior scenes were done on a sound stage in Culver City, Calif. Thus, Meyers instructed her cinematographer Dean Cundey not to take any wide shots inside the cottage so it would feel small and cozy.

11. One of the film's most iconic moments was Law's Mr. Napkinhead performance, with a majority of the scene being improvised, according to Miffy Englefield, who beat out over 2,500 other actresses to play Graham's daughter, Sophie. Englefield revealed to Vulture that Law came up with the line about smoking being bad for you, while Englefield genuinely told Diaz that the bit was "so funny, you'll fall off your chair." 

12. Lindsay Lohan and James Franco make unexpected cameos as the stars of a movie Amanda's company is cutting the trailer for. 

"I know Lindsay because I directed The Parent Trap and I told her she owes me everything so I made her do it," Meyers told ComingSoon.Net of the fake film's origin. "I called her and said, 'You have to do this for me,' but she was sweet about it, she was totally there. James Franco I met at a few dinner parties, we have mutual friends, so I knew him a little bit and I asked him if he would do it and it turned out Lindsay and James knew each other and it was really fun."

13. During a 2006 appearance on The Tonight Show With Jay Leno, Dustin Hoffman revealed his cameo during the Blockbuster scene was unplanned. The Oscar winner happened to be driving by that store and stopped to see what was filming. After talking to Meyers for a bit, she said, "'Wait, I got an idea,'" Hoffman explained. "So she put me in the movie. And like a fool, I didn't negotiate."

14. Amanda's great dash back to the cottage to return to Graham wasn't in the script.

"Literally, I was so fit by the end of that week," Diaz told Vulture last year. "I ran probably seven miles a day in those heels. Through mud and hills. It was so hilarious. I was literally, like, I'm not even complaining right now because my job is to run, and I'm okay with that. But I'm sweating!"

15. An icon in the rom-com genre, The Holiday proved to be "really hard" for Meyers to write after Something's Gotta Give because of the storylines.

"I really wanted to write a broader canvas, but not a broader subject by writing multiple characters and multiple stories and it was actually fun trying to weave them together," Meyers told Coming Soon. "The only conscious thing I did was to not have each girl meet one person. So, on Kate's side of the movie she befriends Eli and that relationship and helps her and guides her. I just thought it would be better for the audience not to have two girls who immediately meet guys and fall in love and have that kind of parallel situation, but it was really fun to write an ensemble movie."