Trivia: The killer's mask was designed by Tony Gardner. If that name sounds familiar, you're probably a big horror fan. Aside from the killer's mask in "Happy Death Day," Gardner also helped design the final look of "Ghostface" seen in the"Scream" franchise (albeit loosely based on an earlier design), worked on a number of cult-films including "Darkman, "Hocus Pocus" and the "Evil Dead" sequels, and has worked as the main effects supervisor on a number of the "Chucky/Child's Play" films.TedStixon
Trivia: There actually is an in-universe explanation for why Tree got stuck in a time-loop. However, director Christopher Landon opted to omit it from the finished film. Partially because it could be used in a potential sequel, and partially because it wasn't necessary for the narrative. Landon has hinted that the upcoming sequel, "Happy Death Day 2U," will finally reveal the explanation.TedStixon
Trivia: The plot of the movie is similar to Groundhog Day which is something that Carter mentions to Tree at the end of the movie. Tree's roommate's name is Laurie Spengler, which is a reference to Egon Spengler, played by Harold Ramis in Ghostbusters. Harold Ramis co-wrote and directed Groundhog Day.
Trivia: "Happy Death Day" shares some pretty interesting parallels to the movie "Before I Fall." Both films feature a young woman who is trapped in a time loop. Both films were released in 2017. Universal Pictures handled the home-video distribution of "Before I Fall" and the theatrical distribution of "Happy Death Day." And Halston Sage and Logan Miller both co-starred in "Before I Fall," in addition to "Scout's Guide to the Zombie Apocalypse," which had the same director as "Happy Death Day."TedStixon