Filmed during the COVID-19 pandemic. Tampere, Finland was chosen as the filming location because of the Finnish government's successful effort to curb corona cases.
The core cast are portrayed as American and the cars have unidentifiable license plates with drivers on the left side. But all the supporting cast are European and the city is shown to have European street signs. This is never explained as the film takes place in an unidentified time period in a presumed America that now has more than 27 Amendments to the Constitution.
Jesse Eisenberg was originally cast but dropped out due to scheduling conflicts. Theo James replaced him.
The horror B-movie that Sarah watches shows a man getting his hand caught inside a sink disposal before being stabbed to death. This is very similar to what happens to Aaron Paul's character in The Last House on the Left (2009).
Karen Gillan's character in Jumanji: Welcome to the Jungle (2017), Ruby Roundhouse, is revealed in that film's sequel Jumanji: The Next Level (2019) to have special skill with nunchucks, and she is delighted to obtain nunchucks and uses them to help win the final battle. In this movie, Gillan's character is reflected in a mirror with a dark silhouette on the wall representing her body, which is prominently holding a pair of nunchucks.