Jennifer Garner Reveals Why 13 Going on 30 Costar Mark Ruffalo Almost Quit the Film

Mark Ruffalo totally lost his poise while filming 13 Going on 30. 

Jennifer Garner revealed that her costar on the 2004 rom-com reached a breaking point during a rehearsal, which almost led the Poor Things actor to drop out of the film entirely.

While honoring the 56-year-old during his Hollywood Walk of Fame ceremony Feb. 8, Jennifer addressed some of Mark's other rom-com costars in attendance, noting, "I wonder if these esteemed ladies enjoyed Mark's anxiety as much as I did."

And the Elektra star—who later teamed up with Mark again on the 2022 Netflix film The Adam Project—didn't hold back on divulging the exact scene that allowed her to witness his rare moment of panic. 

"I wonder if he tried to drop out of their films like he did out of ours after the first rehearsal of the 'Thriller' dance," Jennifer continued, "where Mark went from kind of shocked that we actually had to do this, to antsy, to a deathly quiet, to, 'Bro, this is not for me.'"

Of course, in the end, the Avengers star—who shares kids Keen, 22, Bella Roche, 18, and Odette, 16, with wife Sunrise Coigney—decided to shine up his dancing shoes and stick it out, kicking off what the Alias alum declared as his "rom-com era."

"Honestly, I don't know what you would've done without me," Jennifer quipped. "Thank God I showed up. I have got to be here to honor and elucidate rom-com Ruffalo."

And while the 51-year-old may have been joking, Mark really does credit the actress and their "wonderful chemistry" with keeping him attached to the film. 

He explained to Entertainment tonight in an interview published Jan. 11, "It was Jen Garner, who is just magical." 

Keep reading for more cute moments from Mark's Hollywood Walk of Fame ceremony.

Mark Ruffalo received his star on the Hollywood Walk of Fame on Feb. 8, 2024.

Mark’s 13 Going on 30 costar Jennifer Garner honored him in a moving speech, telling the crowd, "The real success is in how thrilled and delighted your colleagues are to have the opportunity to lift you up and celebrate you." 

The actor was joined by his wife Sunrise Coigney and their children Keen and Bella Roche at the ceremony.

Mark was game to strike the iconic "Thriller" pose with Jennifer from the famous 13 Going on 30 dance scene, despite not being a fan at the time of filming.

Mark and his family were excited about the star, although his third child Odette was unfortunately missing from the ceremony.

Acknowledging that he shares his star with those closest to him, Mark thanked his wife of 23 years during the ceremony. "It's for my wife Sunrise, who's been with me through all of it,” he shared from the stage,” who believed in me more than anybody. You always tell me the truth."

Keen and Bella Noche struck a silly pose with their dad's star.

Mark also received kind words from director David Fincher, who he worked with in the 2007 crime drama Zodiac.