The backstage dressing room where Celeste has a break down before her concert is the same location used in Black Swan (2010) where the main character, Nina, also played by Natalie Portman, has a break down.
Natalie Portman shot her part in only 10 days.
Rooney Mara was attached to the lead role when the project was announced. After the project was put on hold, Mara dropped out and Portman replaced her.