Because of Agatha Christie appearing as a central character in the story, references are made throughout the dialogue to her works. Donna and others drop the names of several of Agatha's works: Why Didn't They Ask Evans, Murder on the Orient Express, N or M, Nemesis, Cards on the Table, Cat Among the Pigeons, Dead Man's Folly, They Do It With Mirrors, Appointment with Death, Sparkling Cyanide (also known as Death Remembered), Endless Night, Crooked House, and Murder at the Vicarage. Also, the book that Lady Eddison reads in a flashback is another Agatha Christie work, 'The Murder of Roger Ackroyd.'
Donna mentions that meeting Agatha Christie during a murder mystery would be as preposterous as meeting "Charles Dickens surrounded by ghosts at Christmas", which The Doctor did in The Unquiet Dead (2005).
In Last of the Time Lords (2007), The Doctor told Martha Jones that he'd like to meet Agatha Christie, saying "I bet she's brilliant."
Agatha Christie's grandson Mathew Prichard was involved in the production, representing Christie's estate, attended the episode's readthrough and gave his enthusiastic approval to her portrayal.
The novel the Doctor produces is from a chest of items beginning with C, including a Cyberman chest-plate from The Age of Steel (2006), a bust of Cicero, and the crystal ball in which the Carrionites are trapped from The Shakespeare Code (2007).
Sandy McDonald: The father of David Tennant stars as a footman. He was visiting David on set and was offered a part on the spot - and he confessed he was glad he didn't have to learn lines.