40 Delightfully Nostalgic Facts You Never Knew About '13 Going on 30'

Although they didn't know each other prior to filming, Jennifer was already a fan of Mark's work. "Five years ago if you had said, 'List three or four actors that you would love to work with,' he would be at the top of my list," she said in Making of a Teen Dream, a behind-the-scenes documentary about the 2004 rom-com.

According to Mark, he and Jennifer initially tried to play their 13-year-old counterparts in the movie's flashback scenes. "It was being talked about for some time, but eventually, they thought it wouldn't work so well," he shared in the documentary. That might be why it took some time to settle on the flashback cast. In fact, the young actors who did eventually take on the teenage roles weren't even in the first iteration of the film, Vulture points out. (No, seriously, you won't recognize these unused clips at all!)

According to director Gary Winick, paparazzi were everywhere during production. "You can't kick them out and they can be in your way, which they were," he revealed. "Of course they were taking pictures of Jennifer every moment they [could]." The paparazzi even tried to snap shots of a kissing scene between Jennifer and Mark, leaving crew members scrambling to cover the actors with cardboard to prevent spoilers.

As a fun nod to the title, Jenna wakes up as a 30-year-old at the movie's 13-minute mark. And the moment when she looks in the mirror to see herself as an adult was inspired by Big, the 1988 Tom Hanks flick with a very similar premise.

And the "Thriller" dance scene was to blame. "Whatever Matty was experiencing in that [scene] was actually just me," Mark said on the ReelBlend podcast, while he and Jennifer were promoting their 2022 Netflix movie, The Adam Project. "[Jennifer] had to drag me onto the dance floor. It took me six hours to learn what she learned in about six minutes. She was so good at dancing, and I was so bad … I almost quit the movie." We're glad he persevered because we can't imagine this movie without him!

Gary shared that he originally wanted to nix the slumber party scene because he believed it took away from the romance — but he later admitted that he thought it was one of the best scenes in the movie.

In a scene that was eventually cut from the movie, Matty convinces Jenna to go to the doctor to figure out what is wrong with her. While in the office, the doctor compliments her tattoo, leaving Jenna scrambling to search her body for the ink.

Mark wasn't the only one with reservations about the number. According to an interview Gary did with The Telegraph, crew members didn't see the point of including the dance, which took some cast members hours of training to perfect — but studio execs insisted on keeping it in the movie because they planned to include the footage in the trailer. Luckily, director Gary saved the day by figuring out a clever way to work it into the plot.

While Jenna and Matty were always going to end up together, Gary originally had a different ending sequence in mind. He wanted the movie to end with their wedding alone (which is still shown), but producers insisted on also showing more of the happy couple's life together, including a scene where they move into a home that closely resembles the film's iconic dollhouse.

The offer came on the heels of Jennifer's 2002 Golden Globe win for her work on the sci-fi series Alias. "I had never just been offered anything before," the actress said in the documentary, adding that her Alias co-stars convinced her to accept the now-iconic role because her personality was so similar to Jenna's.

After landing the role, Jennifer requested to work with Gary, who was known for his independent film career. "When Jennifer was attached to the movie, she chose me as director. She saw Tadpole and we sat down and talked about what I wanted to do with the movie," Gary told the BBC. "We were in the same boat together on this one, really, because it was her first leading role and my first big movie."

In the documentary, Andy, who was known for his role in more serious fare like The Lord of the Rings trilogy, said Gary got frustrated with his over-the-top performance as Richard, Poise's editor-in-chief. "I kind of think I'm doing nothing here and he's going, 'Bring it down.' I'm thinking, 'If I bring it down anymore, I'm going to be lying down," Andy said.

Although Jennifer was the first choice to star in the film, Gwyneth Paltrow, Hilary Swank, and Renée Zellweger were all reportedly considered for the lead role.

Distributors reportedly were worried that the film's name wouldn't translate well in other countries, so they decided to adapt the title accordingly. In Australia, for example, the movie is called Suddenly 30.

The young actress who played teenage Jenna actually hadn't acted much prior to the movie, but Gary said that she had an "awkwardness" about her that was perfect for the role.

"She has that tall thing going on," Jennifer said in the documentary. "Her arms are long and that is exactly how I was at her age. There was more of me than I knew what to do with."

Gary revealed that the young actor seemed too cool for the role at first, so he had to give him some notes. (Marquette also had to wear extra padding to pull off Matty's look.)

Several of the movie's flashback scenes take place in Jenna's basement. And the set decorators didn't have to look too far to make the set look like a family home: The pictures on the back of Jenna's door are actually photos from Jennifer's childhood!

Although Jennifer threw a few of her own moves in there, the choreography for the "Thriller" dance number closely resembles the routine from Michael Jackson's original music video. Movie choreographer Marguerite Derricks told Entertainment Weekly that she ensured Michael Peters, the original choreographer, was credited at the end of the movie.

While scoping out '80s hits to include in the film, the screenwriters said that they eventually landed on "Thriller" because the track evoked childhood nostalgia. "I vividly remember being in my best friend's shag carpeted den sitting ready to watch the world premiere of the 'Thriller' video," co-writer Cathy Yuspa told Entertainment Weekly.