Acclaimed Flop: Despite the fact that many critics seemed to enjoy the movie and the film has gained a cult audience, its box office numbers were terrible (the lowest in the franchise at the time it released), hit with a one-two punch of the release of the much more family-friendly Sonic the Hedgehog (2020) the week after release and the COVID-19 Pandemic striking soon after. The movie at least made back its production budget, but it is believed to have done so at a loss when accounting for marketing costs. It’s also perennially at the top of HBO Max's streaming charts and was singled out as one of the most-streamed movies in the service's first year, on top of being successful as an on-demand release, making this a case of Vindicated by Cable.
Approval of God: Gail Simone (who is considered the definitive writer of the team) has been very effusive in her praise for the movie on her social media after seeing it at the press preview, though she, like many, didn't really care for the film's treatment of Cassandra Cain.
Awesome, Dear Boy: The whole reason this film exists is that Margot Robbie really loves playing Harley Quinn in the DCEU and wants to bring a lot more female characters from DC Comics to the big screen.
Box Office Bomb: The movie's $206 million world wide gross fell well short of its $250 million break even point, resulting in the loss of tens of millions of dollars for the studio.
The Cast Showoff: Jurnee Smollett does her own singing in the film, though she was hired before the director knew she could sing.
Completely Different Title: In France, the full title is the similar but distinct Birds of Prey et la fantabuleuse histoire de Harley Quinn ("Birds of Prey and the fantabulous story of Harley Queen").
Content Leak: A high definition version of the teaser that was supposed to only play in theaters before It: Chapter Two screenings was leaked in early September 2019. It was first leaked in Russian and then in English.
Creator Backlash: Ewan McGregor wished that he had more screen time with the mask on since he wanted to be more scary.
Creator Couple: Ewan McGregor (Black Mask) and Mary Elizabeth Winstead (Huntress) are a couple in real life.
Deleted Scene: A BTS moment had Harley and Joker (a Fake Shemp, not Jared Leto) arguing from a distance through a window on the first floor of the Joker's house. Harley leaves the house through the window and the Joker throws her stuffed beaver out through the window as well. In the film proper, she's just kicked out of the house, with no shot of Mr. J.
Doing It for the Art: This movie happened because Margot Robbie really, really wanted it to happen. She co-funded it with her own production company, and she's gone out of her way to make it a lower budget movie starring a cast of Action Girls. She even hired a female director and screenwriter to make it. On Smollett-Bell's request, she also hired a Black hairstylist to ensure Dinah Lance's hair turned out good.
Dueling Works: With Charlie's Angels (2019). The two films are came out within three months of each other, star an Amazon Brigade, were written and directed by women, and feature a song by Lana Del Rey. Charlie's Angels generated mixed reviews. Birds of Prey got positive reviews and opened higher than Charlie's Angels' entire domestic run ($17 million), albeit still well below expectations.
To what extent is unknown, but Cathy Yan revealed that the studio required her to compromise some aspects of the film, such as the "Diamonds are a Girl's Best Friend"-like dance number dreamed by Harley, the length of which was reduced.
A now-deleted twitter thread confirmed that Cassandra Cain was originally going to be more faithful to the original comics but for some reason, the studio wouldn't allow it.
Prior to the members of the team (Black Canary, Huntress, and Montoya) being confirmed, there was a misconception that Harley was on the team, even though no one involved with the project specifically said that. Though given the film's title and Harley being the main character, it was hardly unreasonable for people to assume such. Ultimately, she does take part in the Origin Story of the team but departs before it is formally established.
In August 2019, there were rumors coming out of a test screening that in that version of the film, the diamond that Cassandra stole contained intimate pictures of Black Mask meant for Zsasz and they were explicitly a couple. These were just rumors spun out of a misreading of the original script, in which the photos were actually of a statue of Roman as Michelangelo's David. They all agreed the joke just didn’t work and therefore it was cut. In the theatrical cut of the film the diamond has bank account information. However, that hasn't stopped a few people calling the film out for "queerbaiting" note more or less marketing off of having LGBT characters but making them But Not Too Gay. No one involved with the project ever said anything about the two of them being gay, the story was based on largely unsubstantiated rumors, and the film wasn't ever marketed for such. Renee's sexuality is treated as no big deal in the film (Ali Wong plays her ex) and wasn't ever brought up in the marketing.
Inspiration Nod: In the background of one scene featuring Renee Montoya is a brief shot of a TV playing an old episode of Days of Our Lives. It features the sequence in the show in which Arleen Sorkin's character, Calliope Jones, dresses up as a clown, which was the original inspiration for the character of Harley Quinn and what landed Sorkin the role as the original Harley in Batman: The Animated Series.
"If this hyena touches anything, it considers it to be his. So we're like, 'Ok can he sit on a couch?' and they're like 'Yes, but then it's his couch. He will eat it and if someone tries to take him away from it, then he'll eat you.' Yikes. Ok, no a real hyena is a no-go - especially if this is how a TRAINED one operates on set. Talk about a diva. So then what?"
No Export for You: Warner Bros. has no plans to release the film in China.
The Other Marty: In the Brazilian Portuguese dub, after dubbing half of the film, Iara Riça (the longtime voice of Harley Quinn) quit following arguments with the dub director and announced her retirement. Evie Saide (who did a fairly close voice) took over.
Daniel Bernhardt, who’s known for playing badass villains, plays Sionis’s driver, who doesn’t have any action scenes, is a sexist thug, is paralysed by Harley, and ultimately gets run over and killed by a van the next morning.
Post-Release Retitle: The movie was originally titled Birds of Prey (and the Fantabulous Emancipation of One Harley Quinn) (to cash in on the popularity of Margot Robbie's portrayal of Harley). When the movie fizzled at the box office, critics pointed out that it was more of an ensemble film than focusing purely on Harley (as well as being one of the most unwieldy official titles ever), and some theatres began marketing it as Harley Quinn: Birds of Prey. It was retitled Birds of Prey or Harley Quinn: Birds of Prey for home release.
Produced by Cast Member: In addition to playing Harley Quinn, Margot Robbie is also one of the film's producers.
Recycled Script: The subplot where Harley has to babysit Cassandra is similar to the story arc Behind Blue Eyes, which is acknowledged as an influence in the DVD "Bird's Eye View" commentary. Like the film, Harley ends up having to watch after a little girl with a secret code (though this time hidden on her retina.) Harley claims at first that the girl means nothing to her, only to start to actually care about her and risks her life to save her multiple times. However, in the film Harley chooses to save Cassandra in the end, while in the comic she still lets Amanda go blind at the end, and is so wracked with guilt after that she willingly goes back to Arkham.
Release Date Change: One of many early 2020 releases to run short on theaters and thus hit home video sooner, due to the COVID-19 pandemic.
In the Latin American Spanish dub, Karla Falcón reprise her role as Harley Quinn from both Suicide Squad and previous adaptations when she appears.
The same goes in the Japanese dub, as Kanako Toujou returns as Harley as well.
Serendipity Writes the Plot: Harley only has a single hyena rather than two because the effects for its photorealistic animation were so intensive they could only afford one.
Margot Robbie and director Cathy Yan both came up with the idea for Harley to shoplift a fanny pack during the chase scene independent of each other (the pack in question was a real product being sold at one of the stalls on location).
Steven Williamsadded: "Miss Montoya, we do have a dress code" at the end of Erickson and Renee's meeting.
Vindicated by Cable: As mentioned above, the movie posted underwhelming box office returns but saw an increase in attention once it was made available as an on-demand feature and a part of HBO Max. This eventually led to a successful push for a Black Canary spin-off film with the streaming service in mind.
Lady Gaga was offered an unspecified role in the film. Gaga would go on to play Harley Quinn in Joker: Folie à Deux.
The Penguin was originally intended to be the main antagonist of the movie, but was scrapped due to his appearance in The Batman portrayed by Colin Farrell.
The breakup between Harley and the Joker (which happens offscreen in the finished film) was actually filmed, complete with a Fake Shemp (musician Johnny Goth) wearing Jared Leto's costume from Suicide Squad. The breakup scene was cut entirely, with both Margot Robbie and Cathy Yan saying that they wanted to make sure the film's focus was on Harley and the heroines.
The climactic fight scene would've originally taken place in a hotel as the Birds fought their way down each floor, instead of a funhouse in the finished product.
There was concept art for a Huntress outfit much more resembling her comic book design.
The original MacGuffin of the plot was going to be photos of a nude statue that Roman commissioned of himself, sculpted in the likeness of Michelangelo's David.
Apparently, a now-deleted twitter thread confirmed that Cassandra Cain was originally going to be more faithful to the original comics, but for some reason, the studio wouldn't allow it.
Laura Kinney is considered Cassandra Cain's Alternate Company Equivalent. In 2017's Logan, Laura was presented as an eleven-year-old played by Dafne Keen. Here Cassandra has been aged down to twelve.note It should be noted that X-23 was a Canon Immigrant created for X-Men: Evolution, where she was depicted as a little girl, not an older teenager like she was reimagined into the comics and other adaptations, so Logan was Truer to the Text in regards to her original Evolution depiction. To add another layer of similarity, the stuntwoman who performed Laura's stunts in Logan, Marissa Labog, also worked on this project.
Though parts of her origin story (including getting her claws fused with adamantium) depicted in "Innocence Lost" and “Target X” has her depicted closer in age to how she is in Logan, she’s still about 15 by the time she meets Logan in the comics.
Ella Jay Basco was so thankful to Margot Robbie for her time on the film that she wrote and recorded a song in character as Cassandra thanking Harley for taking her in.
resulting in the loss of tens of millions of dollars for the studio.