A minor character pf the episode is a theatre lover and mentions her admiration for Henry Irving (1838-1905). Irving was a famous English stage actor in the Victorian era, who also served as the manager of the Lyceum Theatre in the West End of London. He was the first actor to be awarded with a knighthood, indicating his full acceptance into the higher circles of British society. Irving is also one of the main inspirations for the character of Count Dracula, created by Irving's business manager Bram Stoker. Stoker had grown to resent and fear Irving's manipulative tendencies, and consequently used him as an inspiration for his literary villain.
Canon Pennyfather has a concussion, and does not remember his whereabouts for the days of his disappearance. When asked what was the last thing he remembers, he chants the phrase "mirror, mirror on the wall". The reference is to the magic mirror in the tale of Snow White. The Evil Queen of the tale practices catoptromancy (divination through use of a mirror), and asks her magic mirror: "Mirror, mirror on the wall, who's the fairest of them all?"
The sports car of Ladislaus Malinowski is identified as a red Jaguar. Jaguar Cars is a long-running British brand of sports cars and luxury vehicles, with its headquarters located in Whitley, Coventry. It was an independent company from 1935 to 1966. Jaguar has since changed ownership several times, serving as a subsidiary of British Motor Holdings (1966-1968), British Leyland (1968-1984), the Ford Motor Company (1990-2008), Tata Motors (2008-2012), and Jaguar Land Rover (2013-).
Chief Inspector Fred Davy finds it peculiar that Elvira Blake frequently visits London, despite living in Kent. This is far from unusual since the start of the 20th century. Kent is a county in South East England, and is the county closest in proximity to Continental Europe. Kent is one of the so-called "home counties", the counties bordering and surrounding London. Many people living in the home counties are working in London, regularly commuting to work through mass transit.