Natalie Portman revealed that director Darren Aronofsky would subtly try to pit her and Mila Kunis against each other during filming in an attempt to increase the on-screen tension between their characters. This included keeping the two actresses separated during filming and sending each of them intimidating text messages about each others performance that day.
Darren Aronofsky told journalist Kim Masters in a radio interview (KCRW's "The Business" broadcast February 14, 2011) that Natalie Portman not only trained for a year as a dancer to prepare for the role, but paid for the the training out of her own pocket until the film found investors. Aronofsky attributed the film's getting made at all to Portman's dedication and enthusiasm.
In an interview with Charlie Rose, Natalie Portman stated that one of the most difficult challenges of making the film - aside from training and dancing - was modifying her voice. She stated that before working with Darren Aronofsky, directors had constantly criticized what they perceived to be the childish quality of her voice, and encouraged her to work with vocal coaches to make it sound deeper and more adult. The role of Nina required Portman to regress backwards and make her voice more child-like. She felt that doing so took her back to a point she worked hard to leave behind.
Out of all the award nominations the film received the only category sweep was Natalie Portman winning every Best Actress category, including Golden Globe and Academy Award, in which she was nominated.
Mila Kunis was brought into the project after co-star Natalie Portman suggested her to director Darren Aronofsky. Kunis had a video chat with Aronofsky via Skype and got the role without officially auditioning.
The budget on this film was so tight that when Natalie Portman had a rib dislocated during a lift and called the producer for help, she was told that the production could not afford a medic. Portman stated that if they needed to cut items from the budget they could take away her trailer to hire a medic. The next day her trailer was gone. Portman also had to receive physical therapy during filming and one of her sessions was incorporated into the final cut. Choreographer Benjamin Millepied brought in Michelle Rodriguez Nouel, an actual physical therapist, and director Darren Aronofsky told Portman to stay in character during the appointment. Subsequent dance sequences were filmed by having Portman lifted from her arm pits rather than her sides to avoid repeating the injury. It took Portman six weeks to fully recover.
Natalie Portman's body and dance double, Sarah Lane, made a public statement shortly before the DVD/Blu-Ray release in March 2011, claiming that the film's producers asked her not to conduct interviews until after the awards season so Natalie Portman would receive most of the dancing credibility. A promotional video released about the special effects used in the film was also altered so it didn't include aspects of how Lane's face was digitally replaced with Portman's during complicated dance moves Lane was brought in to perform. Choreographer (and Portman's fiancé) Benjamin Millepied counteracted Lane's comments: "It was so believable, it was fantastic, that beautiful movement quality. There are articles now talking about her dance double [Sarah Lane] that are making it sound like she did a lot of the work, but really she just did the footwork, the fouettés, and one diagonal phrase in the studio. Honestly, 85% of that movie is Natalie". Director Darren Aronofsky also debunked Lane's claims: "Here is the reality. I had my editor count shots. There are 139 dance shots in the film. 111 are Natalie Portman untouched. 28 are her dance double Sarah Lane. If you do the math that's 80% Natalie Portman."
Director Darren Aronofsky originally envisioned telling this story as part of the plot of The Wrestler (2008) and was actually developing a project that was about a love affair between a ballet dancer and a wrestler, but he realized pretty quickly that taking two worlds like wrestling and ballet was much too much for one movie.
The method which Nina uses to "break in" her toe-shoes are all common - ripping the sole apart, re-stitching the ribbons, lighting the end ribbons to prevent fraying, spraying the toe-box, and using glass and rosin to grate the bottom to gain traction.
Nina's (Natalie Portman) harmful, compulsive skin picking is an actual impulse control disorder known to the medical profession as Dermatillomania, and may also be referred to as DMT or derm, Neurotic Excoriation, or CSP (Compulsive Skin Picking or Chronic Skin Picking).
In the practice scene near the beginning of the film (when Thomas taps some of the girls on the shoulder), all of the characters except Nina are wearing either all black, or some combination of black, gray, and/or white. Nina is the only character wearing all white.
Sarah Lane, Natalie Portman's dance double, appears in 23 seconds of the opening dance scene. The final 85 seconds of the sequence is unaltered performance by Portman. The 23 seconds in which Lane appears is all en pointe footwork. The dance with Rothbart and the en pointe exit was done by Portman.
Vincent Cassel has compared his character to George Balanchine, who co-founded the New York City Ballet. The actor said Balanchine was "a control freak, a true artist using sexuality to direct his dancers".
The role of the "Jaded Piano Player," the ballet rehearsal pianist who, most memorably, tells Nina that she has been working too hard and she should take a break, is played by John Epperson, a performer who is perhaps better known for his drag persona, Lypsinka. Epperson really did work as a rehearsal pianist for the American Ballet Theatre during the late 1970s and early 1980s, accompanying the rehearsals of such ballet luminaries as Mikhail Baryshnikov, Natalia Makarova, Rudolf Nureyev, Margot Fonteyn, and Gelsey Kirkland.
Days before the DVD/Blu-Ray release, director Darren Aronofsky counteracted accusations made by dancer Sarah Lane, in which she claimed Natalie Portman got credit for her dancing in the film, stating "I am responding to this to put this to rest and to defend my actor. Natalie sweated long and hard to deliver a great physical and emotional performance. And I don't want anyone to think that's not her they are watching. It is." Co-star Mila Kunis also counteracted Lane's comments, "Lane wasn't used for everything. It was more like a safety net. If Natalie wasn't able to do something, you'd have a safety net. The same thing that I had - I had a double as a safety net. We all did. No one ever denied it."
According to a radio interview on "Fresh Air with Terry Gross," Natalie Portman recommended her friend Mila Kunis for the role of Lily after learning that Kunis had previously had some experience as a dancer.
Natalie Portman drew on her ballet training from ages 4-13 for the role. She resumed ballet training a year before principal filming began. She trained with Mary Helen Bowers (formerly of the New York City Ballet) and the regimen included 15 minutes of toe exercises (for her to be en pointe for dance scenes), substantial muscle toning and swimming a mile a day. However, Portman has acknowledged having dance doubles (unnamed) in some interviews. Professional ballerinas Sarah Lane and Kimberly Prosa were the dance doubles for Portman. The special effects team also digitally placed her head on Sarah Lane's body in several dance scenes. Lane did most of the heavy tricks, while Prosa did the rest of the dance shots that were needed. According to both Prosa and Lane in separate interviews, Portman's dance scenes in full body shots were actually the dance doubles. Prosa and Lane also said Portman was filmed dancing from the waist up, showing only face and arms, while the rest of her body dancing were that of the dance doubles.
Though Natalie Portman does mostly all of her own dancing, ABT professional ballerina Sarah Lane acted as her body and dance double. These doubles shots involve complex en pointe work (fouettes, pique turns) and virtually all camera shots that focus below the waist on Nina's legs and feet.
The overhead shot of Nina in the bathtub is an exact replica of a shot in the Japanese anime thriller Perfect Blue (1997). Years before, when making Requiem for a Dream (2000), Darren Aronofsky bought the remake rights to Perfect Blue just to use that one sequence for a scene of Marion (Jennifer Connelly) in a bathtub. Black Swan itself contains numerous similarities, both in narrative and style, to Perfect Blue, though Aronofsky has denied that it was an influence.
The trivia items below may give away important plot points.
While the crew was applying blood to the stab wound on Natalie Portman, she commented to director Darren Aronofsky that she was uncomfortable with the placement of the blood on her tights because it looked like a period. Aronofsky told her he intentionally placed the blood where it was to symbolize Nina becoming a woman. As a result, Portman has stated that she doesn't believe Nina dies at the end of the film. She sees it more as Nina having to kill the little girl in order to mature into a woman.
There is a mirror or a reflective surface in nearly every shot of the film. The only noticeable place where there isn't one is when Nina is on stage, during the film's climax, performing the Black Swan, when her 'dark side' has taken over.
During the dance club sequence most of the people surrounding Nina are either visions of herself, Lily, Thomas, or other aspects of the Swan Lake ballet. The only spot you can clearly see flashes of Nina as the Black Swan on the dance floor is when the voices chanting Nina's name are playing. Although most of them are nearly impossible to pinpoint while watching the film at full speed, there are over 1,000 manipulated images in the 45-second scene.
When Nina (Natalie Portman) calls her mother, Erica (Barbara Hershey), to tell her she got the part of the swan queen, Hershey was unable to be on set that day to interact with Portman over the phone. Director Darren Aronofsky stepped in to be on the other end of the phone call to help Portman get through the scene.
Natalie Portman has stated it was "really uncomfortable" to film the sexually explicit scenes, but she believed the scenes were necessary to show Nina's discovery of self pleasure as part of her evolution.
An online rumor broke out shortly after the film's release claiming that Natalie Portman and Mila Kunis took shots of tequila before shooting their lesbian sex scene and were drunk on screen. Kunis denied the rumors shortly after saying, "I don't think we could have done that scene if we were intoxicated."
When Nina completes her performance as the Black Swan and poses onstage, the wide shot shows her from the audience's perspective without her imagined feathers; however the feathers are still visible in her two silhouettes.