Continuity mistake: When Tree looks at her iPhone it shows the time as 9:23 when the power goes out. Then when the TV is shown the time on that clock is 9:24, when she walks to the TV the time is then 9:31, and then the next view of the clock shows the time back at 9:24.
Happy Death Day (2017)
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Directed by: Christopher Landon
Starring: Israel Broussard, Jessica Rothe, Ruby Modine, Charles Aitken, Rachel Matthews
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More mistakes in Happy Death Day
Lori Spengler: How did you figure it out?
Tree Gelbman: Because you've killed me before.
Lori Spengler: Then I guess I'm just going to have to do it again.
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.