Asa Butterfield's character is called Billy Rubin. Bilirubin is an organic compound present in excrement. Peter Strickland may have borrowed this reference from The Silence of the Lambs. Similarly, Fatma Mohamed plays a character called Elle di Elle. LDL Cholesterol is also known as the "bad" cholesterol. Ariane Labed plays a character called Lamina Propria, which is the name for a type of connective tissue found under the thin layer of tissues covering a mucous membrane.
Gwendoline Christie(Jan), Fatma Mohamed(Elle) and Richard Bremmer(Dr. Glock) all appear in the film "In Fabric" (2018). Both movies were written and directed by Peter Strickland.