Zach Cregger initially eyed Companion as his directorial follow-up to Barbarian (2022), though the team wound up setting the project as the directorial debut of Drew Hancock.
The name Iris is "Siri" backwards.
Kat opens Sergey's safe by entering the date of Stalin's birth (18 December 1878). The keys she presses are *181278 indicating the filmmakers' attention to details: a Russian like Sergey (as the majority of the rest of the world) would use the day-month-year date format instead of the US standard month-day-year.
Josh (Jack Quaid) is listening to "Iris" by Goo Goo Dolls in the scene where Iris gets delivered to his residence. Quaid's mother, Meg Ryan, starred in City of Angels (1998), for which this song was written.