Tom Baker later revealed on his DVD commentary for "The Robots of Death" that he was surprised there had been no rehearsal for the actors when he made this guest appearance on Miss Marple.
The original 1944 novel has Superintendent Battle as the chief investigator and does not feature Miss Marple at all.
Cameo appearance by the famous tennis player Greg Rusedski. He plays Merrick, who beats Neville Strange at Wimbledon a few minutes in.
The tennis match scene at the beginning of the movie shows the Centre Court scoreboard with "incandescent-lightbulb" display installed in the 1950s. All the Wimbledon displays since then have been made to reflect the same design. The one in the programme has been made to look period with some misaligned and non-functioning bulbs.
The original novel "Towards Zero" was published in 1944, and the main character was another of Agatha Christie's recurring cast members, Superintendent Battle. "Towards Zero" was Battle's fifth and last appearance in a Christie novel, following large roles in "The Secret of Chimneys" (1925), "The Seven Dials Mystery" (1929), and "Cards on the Table " (1936), and a cameo role in "Murder is Easy" (1939).