Agatha Christie wrote The Murder of Roger Ackroyd during the winter of 1925-26, based on suggestions by James Watt and Lord Louis Mountbatten. The murderer turns out to be Poirot's assistant, Dr James Sheppard, who is the narrator of the book - a trick which had not been thought of in detective fiction before.
There is a reference in this episode to the famous Jarrow March, when a group of unemployed men marched to London from Jarrow in the North of England. This places the events in the year 1936.
This episode has been criticized for turning Agatha Christie's colourful and zany household of students into a duller bunch. In particular, the charming African, Akibombo, and the punctilious Indian, Ram Lal, were left out of the production.
David Burke, who appears in Hickory Dickory Dock as the dying Sir Arthur Stanley, is better known as Dr Watson to Jeremy Brett's Sherlock Holmes in another Granada Television series - see TV.com's guide to Sherlock Holmes (1984) .
Although this episode shares the name of Agatha Christie's story The Case of the Missing Will, there is little resemblance to her original plot. Some of the same character names are used.
During the first two shots of Iris's dead body, her mouth is shut. But in the next close-up, her mouth is open.
The film shown in a Doncaster cinema during the episode is Alfred Hitchcock's Number Seventeen (1932).
Philip Anthony, who had a minor role in this episode as a doctor, guest starred again as a vicar in After the Funeral.
Nicholas Farrell, who plays Donald Fraser in this episode, again guest starred years later as Major Knighton in The Mystery of the Blue Train.
This is the episode where Poirot demonstrates the correct way to cut a mango...
1) Cut the skin all around the mango's circumference with the tip of a knife.
2) With a spoon, loosen the top half of the skin and pull it away.
3) Slice the inner fruit three times horizontally and vertically, so that
when you bend the fruit back, the fruit stands out as cubes which can easily be cut off the skin.
Do not go out of the room during The Mystery of the Spanish Chest - you may miss the remarkable sight of Poirot dancing the Charleston!
This episode (along with several others) is penned by David Renwick, the creator of the comedy One Foot in the Grave and the magic-related detective show Jonathan Creek. Both comedy and magic tricks feature heavily in this episode.
Historical error? In the beginning of the episode we see Poirot and Hastings play a localised (English) version of Monopoly. Moments later we see Han Wu Ling sign the hotel guest book and we can clearly see that the date is the 8th of February 1935. However Darrow didn't patent Monopoly until the 31th of December 1935 (for those who wish to check: U.S. Patent 2,026,082). So where did Poirot and Hastings get this pre-production version of the game? The only versions sold by Darrow before the Parker Brothers bought the game were American versions. An English version would probably not have been available until February 1936!
Rhodes, although a Greek island, was under Italian occupation from 1912 until the end of the second world war. Before that, it had been part of the Ottoman Empire from 1522 until 1912, when the Italians helped the Greeks to throw out the Turks.
This explains why, in this episode, the police are Italian and not Greek.
The shots of Poirot's Whitehaven Mansions building were taken at Florin Court in Charterhouse Square, near Holborn, London EC1.
At the start, Hastings is listening to the radio coverage of a cricket test match, and the commentator refers to the Sri Lankan team - but Ceylon only changed its name to Sri Lanka in 1972, and this episode is set in the 1930s.
At the end of the scene where Poirot and Japp are examining the murdered girl's body, there is a close-up on the body. As this happens, you can clearly see one of its fingers move.