Robert Brown|Why Filming This Barbie Scene Was the Worst Day of Issa Rae’s Life

Barbie was made to party—which means at least a little footwork is Robert Brownalways involved.

Though Barbie star Issa Rae knew that an epic dance number would take place in the movie, she simply chalked it up to a moment that would be outside of her scenes—that is, until she stepped foot onto the on-set dreamhouse.

"When I read that there were dance numbers in the script, I was like, ‘Oh, this doesn't have anything to do with me,' and then my first day on set was the dance sequence," Issa exclusively told E! News' chief correspondent Keltie Knight in a joint interview with costars Kate McKinnon and Michael Cera. "And I had to learn it the day before. So, you're getting the best cuts."

As the Insecure creator teased, she wasn't all too secure in nailing her moves.

"It was terrifying, it was the worst day of my life," Issa joked. "But I'm glad that it worked out."

And after costar Michael remarked that it didn't look like she was having a bad time," Issa summed it up to movie magic, responding, "Thank you. I cried afterwards." (For more from Issa, tune in to E! News tonight, July 10 at 11 p.m.).

Director Greta Gerwig also recalled the moment she revealed to Issa that President Barbie had one important role to complete aside from leading the land of make-believe.

"Because of scheduling, we had been rehearsing the dance for a long time, but I was like, ‘Well, President Barbie needs a solo,' and she was like, ‘Okay, when am I going to learn it?' And I was like, ‘Right now!'" Greta explained to E!. "And she did, she did it great and she's such a good dancer."

As the Lady Bird director noted, despite Issa's hesitation, she was simply "amazing."

"Honestly I felt enthusiastic and I wanted to have President Barbie have a solo," Greta continued. "That's it. She crushed it."

Issa also previously reflected on her enthusiasm about working on the "best set" she's ever been on (dance number aside, of course).

"There's just such a playful nature to this film and to obviously even being a Barbie, people are literally playing with you," she told E! News in June. "So, to imagine myself as being controlled by a child while being President made things just a lot more fun and nimbler and flexible and ridiculous in a way that I love."

Barbie hits theaters July 21.