The raw chicken that Justine eats out of the fridge is actually sugar. Garance Marillier has commented that the scene didn't put her off chicken from then on, but it did put her off from candy for life.
Director Julia Ducournau really wanted actress Garance Marillier to work on her body and posture. A drastic change is visible between the beginning and the end of the movie. Garance Marillier's posture changes as her character transforms.
Due to the graphic nature of the film, ushers at the Nuart Theatre in Los Angeles (USA) were handing moviegoers custom-made vomit bags.
At a screening at Gothenburg Film Festival, several attendants in the audience fainted and vomited. Over 30 people left the cinema prematurely and they had to take a break in the middle of the movie due to all the turmoil.
In the scene where Justine dances in front of the mirror, she is listening to the gothic rock/rap duo "Orties," a band made up of two twin sisters who often rap about men in the traditional way that male rappers talk about women.