The title of the film was misspelled as "Ghost Storeis" in much of the pre-release media. This was done to accord with the production's tagline "The brain sees what it wants to see"
The exposing of the psychic at the beginning is based on a real event. Televangelist and supposed faith healer Peter Popoff was caught by skeptic and magician James Randi. Popoff would have people fill out prayer request cards before events. Randi intercepted the radio signals from Popoff's wife, feeding him information from the cards, into his hidden earpiece.
Similar to the number's theme, all clocks and watches are set to 3:45.
Based on the West End play by League of Gentleman writer Jeremy Dyson.
The satyr woodland creature 'Woolly' is played by experienced creature performer Paul Warren, who has also played creatures in Star Wars: The Force Awakens, The Last Jedi, Guardians of the Galaxy and Thor: The Dark World.