The paintings in the film were done by the film's production designer Eve Stewart and by British artist Susannah Brough. The film's paintings weren't exact replicas of Gerda Wegener's work, they had to be to adapted because they didn't look like Eddie Redmayne. The original portrait of ballerina Ulla Poulsen, was also altered to resemble Amber Heard's face.
Lili consulted two physicians, both of whom diagnosed her as homosexual, a third physician diagnosed her as intersexed and claimed she had rudimentary female sex organs. In fact, when the sex reassignment surgery commenced, the surgeons found shrunken female ovaries. Hormonal assays taken just before her first surgery indicated more female than male hormones present. It is likely that she had XXY sex chromosome karyotype (Klinefelter's Syndrome) a condition not medically recognized until 1942. The fact that Lili was Intersex is not mentioned in the film.
Einar Wegener/Lili Elbe wasn't the first transgender person nor the first to undergo sex reassignment surgery, she was only among the first. Dora Richter/Dörchen Richter (also known as Dora R., 1891-1933) - who was born as Rudolph Richter, became the first trans woman of whom records remain to undergo vaginoplasty. According to Dr. Felix Abraham, a psychiatrist working at the Institute for Sexual Science, where Dora was employed as a domestic servant, her first step to feminization was made by means of castration in 1922. After this there was a long pause, until the beginning of the year 1931, when the penis amputation was done and in June, the here described surgery - a highly experimental vaginoplasty performed by Dr. Erwin Gohrbandt, who later becomes a decorated surgeon-general in the Luftwaffe. Carla van Crist and Toni Ebel had also got the surgery before Lili arrived in Berlin. The Institute for Sexual Research (founded by Magnus Hirschfeld in Berlin, in 1919), was doing the operations, but the Nazis destroyed the files in 1933 so there is no way of knowing who truly was the first person to undergo sexual reassignment surgery. Lili's last operations were made by Dr. Kurt Warnekros at the Dresden Women's Clinic. Her first surgeries (castration and penectomy) had been performed by Dr. Ludwig Levy-Lenz under Hirschfeld's supervision in Berlin in 1930. These preliminaries have sometimes caused confusion over the date of Lili's 'sex change', but Dora/Dörchen Richter was the first transgender woman who underwent sex reassignment surgery, that began in 1922.
The real Einar / Lili had two siblings, one brother and one sister, who were aware of her transition and although were conflicted, they were nonetheless supportive. Einar / Lili's parents had already passed away by the time the transition had commenced. The film does not include nor mention her siblings.
When Nicole Kidman was set to star and produce the film, she struggled to sustain an actress to portray Gerda Wegener, while she would portray Einar Wegener herself. Charlize Theron was the first choice for Gerda, but dropped out in 2008. Her role was then given to Gwyneth Paltrow, who also dropped out in order to spend more time with her family. Uma Thurman was rumored to replace her. In 2010, Marion Cotillard was considered for the part, as she and Kidman wanted to re-team after working together on Nine (2009), and their other possible project "The Rivals" had been shelved. In 2011, the role was given to Rachel Weisz, who also dropped out soon after. Alicia Vikander took the role in 2014, when Tom Hooper took over the project.