'Birds of Prey': Why Harley Quinn's hair tie exchange and lack of a love interest are so significant

Warning: Minor Birds of Prey spoilers ahead.

Birds of Prey (And the Fantabulous Emancipation of One Harley Quinn) is the first ever female team-up comic-book movie, with Margot Robbie's eponymous antihero joining forces with Black Canary (Jurnee Smollett-Bell), Huntress (Mary Elizabeth Winstead) and Renee Montoya (Rosie Perez).

But there's just as significant a team-up behind the scenes: It's also the first comic book movie written and directed by women, and they're a pair of rising stars in their own fields: Christina Hodson, who penned last year's acclaimed Transformers spinoff, Bumblebee, and Cathy Yan, the filmmaker behind the 2018 Sundance breakout Dead Pigs.

As fans have been pointing out on social media, Hodson and Yan’s female perspective paid huge dividends in bringing a new authenticity to the film.

Case in point: During a climactic fight scene, Canary casually asks Harley for a hair tie, mid-fisticuffs.

"Women always seem to have perfect hair and perfect makeup, even if they're fighting, even if they've been upside down and doing crazy stuff. They always seem to have perfect hair, and it always seems to be down," Yan told Yahoo Entertainment (watch above). "So we just wanted to make a cheeky sort of nod to that if you will. I was OK with them not looking perfect all the time."

Hodson credited her sister Tandy for the idea. "I'm so happy that it is getting the attention that it's getting because it is such a tiny detail," she said. "We always laugh about the fact that women go into [battle in] action movies with these long, flowing perfect locks. When in real life, neither of us would ever even sit down to eat a meal with our hair down."

The interplay between the female film-making team also resulted in another detail that has gotten some attention: The revelation that Harley voted for Bernie Sanders (a “grievance” listed against her by Ewan McGregor’s villainous Black Mask). So the Vermont senator and Democratic presidential contender exists in the DC Comics Extended Universe. “Only Bernie, though,” Yan laughed, crediting the “Easter egg” to Hodson.

Explained Hodson: “She probably just did it because she thought he was a cute old man,” the writer cracked. “Like, ‘Look at his cute little hair.’”

Yan and Hodson consider Birds of Prey a standalone film — and, yes, while it's not a direct sequel to 2016's much-maligned Suicide Squad, which introduced Robbie's take on Quinn — it does launch from that film's events. And that's namely in liberating Harley from her ex-boyfriend Joker, or "Mr. J" (Jared Leto).

There's no rebound in sight for Harley in Birds of Prey. "I do think it's really nice that it's a group of women, and it's not about relationships with men," Yan said. "It's really nice and refreshing."

In fact you could argue the closest thing Harley does has to a love interest is the egg sandwich, the breakfast dish she practically fantasizes over throughout the film's course of wild events.

Hodson said Harley's egg sandwich fascination came from her own obsession with food.

"And Margot and I eat a lot of food together, we like food. And when I came up with that idea I was like, 'I'm pretty sure she'll like this.' And she was like, 'Yes, this makes perfect sense. Of course we would have a large chunk of the movie dedicated to an egg sandwich."

Birds of Prey is now in theaters; visit Fandango for showtime and ticket information.

Watch the trailer:

Read more on Yahoo Entertainment:

• Where's Batman? Is the Joker dead? Your burning 'Birds of Prey' questions answered (spoilers!)

• Jared Leto's revenge? 'Morbius' trailer premieres in wake of 'Birds of Prey' demise, 'Joker' nominations

• The It List: 'Survivor' celebrates 40 seasons, Margot Robbie's Harley Quinn returns in 'Birds of Prey,' Jessica Simpson launches tell-all memoir and the best in pop culture the week of Feb. 3, 2019