Cameron Waldrop
That film is The Last of Sheila from 1973, and it’s about a movie producer inviting his closest friends on a week-long yacht trip scavenger hunt a year after his wife’s death. You can likely see the Glass Onion inspiration with that summary, considering it is about a rich businessman inviting friends on a trip to play a murder mystery game. While it’s not required to enjoy the new Rian Johnson film, it can’t hurt to watch The Last of Sheila before you stream Glass Onion on Netflix just to get yourself in the mood from one mystery film to the next. Johnson even tweeted about it last year and again when it was set to air on Turner Classic Movies back in August. There is, however, one rather direct connection between the two films. The Last of Sheila was written by the late Stephen Sondheim and Anthony Perkins. However, Stephen Sondheim made his last on-screen appearance in Glass Onion during the scene in which Benoit Blanc is having a zoom call with several celebrities. It can be assumed this was orchestrated by Johnson to pay homage to one of his heroes. Also, on that same call is the late Angela Lansbury, the star of the murder mystery series Murder, She Wrote.

Glass Onion Proves Knives Out Is a Murder Mystery Franchise With Endless Possibilities Sus, She Wrote! Angela Lansbury Taught the Among Us Basics for Glass Onion Cameo Should You Watch The Last of Sheila Before Glass Onion: A Knives Out Mystery? Explained Glass Onion: A Knives Out Mystery vs Knives Out, Which Movie Is Better Glass Onion: A Knives Out Mystery Has a Cute Callback to the Original & Serena Williams Is Involved
PSA  You Should Watch The Last of Sheila Before Glass Onion  A Knives Out Mystery - 7