This was Alex Trebek's final appearance in a movie. He passed away from cancer on Nov 8, 2020, nine months before the release of the film on August 13, 2021. His last day in front of a camera was on his final taping of Jeopardy! (1984), which was on October 29, 2020, ten days before he died.
A map of Free City, the city that the game in the film takes place in, is actually a map of Portland, Oregon. The "stash house" that Jodie Comer's character wants to break into is shown as being located in Portland's Forest Park.
Ryan Reynolds personally talked to Mariah Carey for the rights to use her song "Fantasy" in the film. The rights issue was a little complex, however, as the song was directly sampled from the Tom Tom Club hit, "Genius of Love" (1981), the live version of which can be found in the Talking Heads concert film, Stop Making Sense (1984). Tom Tom Club was essentially Talking Heads without its leader, David Byrne. Samples of Genius of Love have appeared in over thirty songs attributed to other artists.
(at around 15 mins) Shortly after Guy buys his new shoes, a gin bottle-shaped power-up on the floor titled "Subtle Product Placement" is visible over his shoulder. It's likely a reference to Aviation American Gin, which Ryan Reynolds had a stake in and maintains an ongoing ownership interest.
Three of director Shawn Levy's four daughters appear on screen. They play Tween Gamer Girl, Foul Mouthed Little Sister, and Big City Dreamer.