Trivia

Agatha uses the under cover name of Mary Westmacott in the drama. The real Agatha Christie published 6 novels under this name between 1930 and 1956: The Rose and the Yew Tree, the Burden, Absent in the Spring, Giant's Bread, Unfinished Portrait and a Daughter's Daughter.

The book that Agatha reads to Rosalind is R.U.R. by Karel Capek, published in 1920; this book is credited with introducing the word "robot" to the English language.

The opening card states that the details of Agatha Christie's disappearance on 3 December 1926 have never been revealed. She was found 10 days later at a spa in the country registered as Mrs Tressa Neele (the surname of her husband's lover). Speculation as to her state of mind during this time remains a mystery; with some believing she was suffering temporary amnesia, or deliberately trying to embarrass her husband even to the point of framing him for her murder, or simply hiding. The incident was not mentioned by Christie in her autobiography.

The framed copy of 'The Daily Sketch' in Agatha's study makes reference to Henry Segrave: famous racing driver and land speeds record holder. Segrave was a contemporary of Agatha Christie and like her husband Archie, a member of the Suicide Club (the name given to Royal Flying Corps pilots during WW1).

Randolph states that he served in the Great War, but worked in administration. Tim McInnerny (Randolph) played pencil-pusher Captain Darling in Blackadder Goes Forth (1989).