The subtle beeping sounds in the background for all the evening outdoor scenes are made by frogs, which are very common in the Caribbean.
Her advancing years, the Caribbean heat and the gruelling shooting schedule prompted Joan Hickson to worry about her line-remembering skills. Cue cards were therefore thoughtfully supplied by the production team, in case the actress felt needed them. She did not.
Joan Hickson had originally intended for this to be her final appearance as Miss Marple but she was persuaded to return for Miss Marple: Le manoir de l'illusion (1991) and Miss Marple: The Mirror Crack'd from Side to Side (1992).
Shooting took place at the Coral Reef Club in Barbados, the same hotel previously stayed in by Agatha Christie and her daughter Rosalind Hicks (the BBC's link with the Christie family). It was reportedly largely unchanged, and their logging-in details were found by the production team in the establishment's records. English emigrants Budge and Cynthia O'Hara had arrived on the island in the 1950s, having spent their honeymoon on a passenger cargo ship, and never left; consequently they were still running the venue when the BBC arrived. Elements of Tim and Molly Kendal were supposedly derived from them by Christie.