Margot Robbie rolled with actual roller-derby pros for Birds of Prey role

Birds of Prey (And The Fantabulous Emancipation of One Harley Quinn) showed off its antiheroine's titular emancipation in as many messed-up ways as possible. Shooting up a police station, getting crazy drunk, cutting her own hair, and — yes — even roughing up some folks at the roller derby. Star Margot Robbie may have had some experience with stunts, skates, and supervillains thanks to her previous filmography, but shooting her rollerskate-centric fights required an expert's touch.

The process behind this is put on full display in one of Birds of Prey's special features from its digital release, out now. Director Cathy Yan's film came stuffed with extras, and one was all about the film's New 52-inspired roller derby. "In the New 52 comic, there's a roller-derby fight-club situation," Robbie said. "I love that comic book. I kept saying, 'We have to have roller derby, we have to have roller derby.'"

Enter the film's skating technical advisor: Rachel Rotten. She and Robbie's skating stunt doubles, Jocelyn Kay and Michelle Steilen, helped craft the early scene where Harley trucks some ladies on wheels. "She's the only comic book character on roller skates," Steilen said. "The roller-skating community loves Harley Quinn. The fact that she's on skates in a film? We're gonna go crazy over this."

That scene's skaters are all roller-derby pros, which meant that those behind the camera didn't need to worry about their abilities — this is just what those pros do. "We are introduced to [Harley] skating as a very aggressive roller-derby player," Rotten said. "That aggression has to carry throughout the film and into the other action scenes that feature the roller skating. There is absolutely an element of who Harley is and how Margot will have to skate."

This meant learning a totally different kind of movement. "It's really about getting her as comfortable on wheels as she was on ice," Rotten explained, referring to Robbie's Oscar-nominated performance as Tonya Haring in I, Tonya. "I definitely underestimated how hard it would be, because I thought, 'Oh, I've done I, Tonya, I've done a lot of ice skating — throw some wheels on and it'll be the same thing.' It definitely wasn't as painful as ice skating, I have to say."

Learning to stop on a dime and learning to embrace all the speed that comes from being whipped around by another skater were just a few techniques that Robbie needed for her scenes. Then, when it came to the crazier parts of the fights toward the end where Harley is wearing the skates, Robbie's primary stunt double, Renae Moneymaker, stepped in.

"Doing a fight scene is difficult in its own right, but then you put roller skates on your feet and it changes everything," Moneymaker said. "Margot is so good on the skates that anything short of those bigger double gags, she was able to do just fine." But doing some of the flip-fighting that blended gymnastics, skating, and martial arts? Moneymaker took the wheel there. Rachel Rotten would be proud.

Birds of Prey is out on home video now.