The story Morse is told about a portrait of a cast of a drowned woman is an actual one. Known as "L'inconnue de la Seine", she was a woman found in the Parisian river in the late 1880s and presumed to be a suicide since there were no marks of violence. She was never identified, but was seen as the epitome of female beauty and copies of her death-mask did indeed become must-have household objects from around 1900. Her face was used as the basis for the original 1958 CPR mannequin, "Resusci Anne".
After JCN has won the chess-match there is champagne going around. Professor Amory offers some to Professor Gradenko but he declines; to which Armory then says: "Come on old chap, Napoleon's dictum". Here he refers to the quote of Napoleon which states: "Champagne! In victory one deserves it, in defeat one needs it."
WPC Trewlove refers to a chess gambit as "Kronsteen's variation" - a reference to the chess master played by Vladek Sheybal in the film From Russia With Love.
The piece played on the glass harp at the beginning is Gnossienne n.1 by Erik Satie. The original arrangement is for the piano but an orchestral version arranged by Rachel Portman for the movie Chocolat (which plays during the flashback "Story of Grandmere and Grandpere") is also well-known.
The fictional Lovelace College is named after Augusta Ada King-Noel, Countess of Lovelace, or Ada Lovelace for short, often referred to as "the first computer programmer", after her work with Charles Babbage on his Difference Engine.
Colin Dexter: photo on the wall of Dorothea Frazil's newspaper office. Notably, it was announced in January 2017 that Dexter, author of the original Morse novels, had retired from his frequent role as extra and would no longer appear in the flesh on television. Dexter passed away a few months later, March 21, 2017.