Sasha Calle had talks with DC and Warner Bros. about reprising her role from The Flash (2023), before the creative change on the franchise.
Inspired by the comic book arc "Supergirl: Woman of Tomorrow" by Tom King. The story updated Kara's character as a 21-year-old young woman adventuring in the depths of space.
Milly Alcock is the fifth actress to portray Kara Zor-El in live-action and the third in film after Sasha Calle and Helen Slater.