Margot Robbie has had a busy and buzz-worthy year starring in two Oscar-nominated films -- and she tacked on another title to her resume that meant running from one set to the next to reprise her role as Harley Quinn in "Birds of Prey."
Robbie joined "Good Morning America" Tuesday alongside three of her co-stars, Rosie Perez, Jurnee Smollett-Bell and Ella Jay Basco, to chat about the DC comic book series-turned-movie that she executive produced.
"'Bombshell' overlapped with our pre-production, so I would go from set to the office, back to set back to the office. And then 'Bombshell' also overlapped with 'Once Upon a Time [in Hollywood],'" she explained. "It was just madness. Thank goodness it was all in L.A."
The action film centers around Harley Quinn after her explosive breakup with Joker as she joins superheroes Black Canary, Huntress and Renee Montoya to save a young girl from an evil crime lord.
"You really see Harley becoming her own woman in this movie," Robbie said. "The film itself is about seeing the formation of the Birds of Prey coming together, and we kind of needed Mr. J out of the picture to spend time getting to know the other characters."
Perez, who plays Renee Montoya, said that being a part of the first all-female superhero ensemble film, with all women at the helm of its production, was unlike any experience in her career.
"I've had the privilege in over 30 years in this business to work with female directors and producers, but never on this magnitude, never on a studio level big budget film -- I hope it continues," Perez said.
"And I have to say," she added, "this is one kick-a-- executive producer."
Smollett-Bell, who plays Black Canary, said they trained for "over five months to be able to do most of the stunts in the film," and even though they "felt powerful and strong," she admitted the rigorous action "kicked our butts."
Basco, 13, however, had a slightly different style of training to prepare for her role as Cassandra Cain.
"I did do a lot of magic training, so I worked with a magician from the Magic Castle -- he taught me some sleight-of-hand and how to steal some wallets and money," she said with a laugh.
If the DC film gets a sequel, the executive producer and star shared the character she'd love to see make an appearance.
"I'd love to see Poison Ivy on the screen again, I love her," Robbie said. "If we're talking Birds of Prey, Oracle would be a pretty integral part -- I hope after this film they can kind of shoot off in the universe, it'd be cool to bring them in."
MORE: How 'Bombshell' made star Margot Robbie rethink sexual harassment"Birds of Prey" hits theaters nationwide on Friday Feb. 7.
Robbie is nominated as actress in a supporting role for "Bombshell," and "Once Upon A Time... in Hollywood" is nominated for best picture.
Watch the Oscars Sunday Feb. 9 live on ABC and check back to GMA for full coverage from the red carpet to the list of winners.