The scene of Holmes burying his syringe came in reaction to the producers and Jeremy Brett learning that this Sherlock Holmes was very popular with children, who saw him as a superhero. As such, Brett was troubled that Holmes was setting a bad example to that audience with his cocaine usage. In response, he sought and obtained permission from Arthur Conan Doyle's daughter, Dame Jean Doyle and the Doyle estate for permission to have Holmes overcome and abandon his addiction.
After being rescued by Watson, Holmes calls Watson by his first name, "John". This is the first time in the entire literary, cinematic and televised history of Sherlock Holmes that one of the two main characters addresses the other by his first name; in all other instances, the surname ("Holmes", "Watson") is used.
The hallucination segment includes details of William Blake paintings (Nabuchodonosor, The Body of Abel Found by Adam and Eve) and scenes of Holmes' encounter with Professor Moriarty from The Final Problem (1985).
The story of a drug that produces such bizarre results had been considerably ridiculed until the development some decades later of a synthetic compound named lysergic acid diethylamide or, commonly, LSD. The hallucinatory effects are almost exactly those of the root powder in the story. Since LSD is prepared from a natural alkaloid, it is conceivable to assume that such a compound could exist in an as yet unidentified root. LSD was first made by Albert Hofmann (11 January 1906 - 29 April 2008) in 1938, 20 years after 'The Devil's Foot' was first published.
Gary Hopkins's script for this episode won the series its second of two Edgar Allan Poe Awards from the Mystery Writers of America.