The mask designer for "Heart Eyes," special effects artist Tony Gardner, also created the killer masks for "Freaky," "Happy Death Day," and "Totally Killer."
A news ticker early on in the film mentions the remains of a mailman being found under a bed and breakfast in Vermont, a nod to director Josh Ruben's previous film, Werewolves Within.
When Monica and Ally shop for clothes, Ally's clothes reference other romantic comedies. Her first outfit with the hat is Stacey Dash's from Clueless, the dress with the collar is Julia Roberts' night outfit from Pretty Woman, and then she and Monica wear the colored dresses from Romy and Michele's High School Reunion.
Director Josh Ruben said that he wanted all of the romantic moments to feel as Nora Ephron as possible while having the horror moments feel as Wes Craven as possible.
The two detectives investigating the Heart Eyes Killer murders are named "Hobbs and Shaw," a reference to "Fast and Furious" . The screenwriters confirmed that had always been the case, even before Jordana Brewster, who has played a large role in the series, was brought on as Detective Shaw.