Trivia: The contract in the film stating no film can be made of The Mousetrap until 6 months after the theatrical run ends is actually true in real life as well, albeit only referring to English language versions. To date there have been Bengali and Russian films made of the play. The Mousetrap has been running near-continuously since it began, except for a break during the pandemic of just over a year.
Trivia: The storyboards shown for the proposed "action" finale of the Mousetrap film mirror the actual finale of this film.
Trivia: The "Rillington Place" murders referenced were real crimes, committed coincidentally by a man called John Christie. Sir Richard Attenborough played him in a 1971 film.
Trivia: Leo Köpernick's name was deliberately chosen to reference two British slang terms relating to police/crime: "Copper", meaning a police officer, and "nick", meaning to arrest someone.
Trivia: Sam Rockwell took inspiration from Peter Sellers' Inspector Clouseau for his portrayal of Inspector Stoppard, albeit with Peter Sellers' natural accent and more competent.
Trivia: This film was originally in development in 2016 with Hugh Grant and Keira Knightley starring, but put on hold after Disney bought 20th Century Fox.
Trivia: Sheila says of the director "He was a real hound, Inspector". The Inspector's name is Stoppard, named for writer Tom Stoppard, who wrote "The Real Inspector Hound".
Trivia: The hotel concierge is from Belgium but mistakenly thought to be from France, just like Poirot, another Agatha Christie creation.
