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.
No year is given in the film. However, Josh's phone reads "Sunday, June 25." In the 21st century, June 25 falls on a Sunday in 2006, 2017, 2023, 2028, 2034, 2045, 2051, 2056, 2062, 2073, 2079, 2084, and 2090. In the 22nd century: 2101, 2107, 2112, 2118, 2129, 2135, 2140, 2146, 2157, 2163, 2174, 2185, 2191, and 2196.
The opening scene of the film where Sophie Thatcher is pushing a grocery cart echoes the last scene of The Stepford Wives (1975) where Katharine Ross is also pushing a grocery cart.