Charlize Theron was the first choice for Greta Wegener but dropped out. Her role was then given to Gwyneth Paltrow, who also dropped out in order to spend more time with her family. Marion Cotillard was considered too. The role was then given to Rachel Weisz who also dropped out soon after.
Tomas Alfredson was going to direct but dropped out.
The true origin of Gerda Wegener (Gerda Gottlieb Wegener Porta (15 March 1886 - 28 July 1940)) is Danish, not American. The novelist changed her origin to American to suit the American readers. Not to be confused with German makeup artist Gerda Wegener.