For location shooting, K-9 was equipped with a small microphone and speaker, so that John Leeson could hear and interact with the other actors from a van parked nearby. One day, while waiting for a scene to be set-up, Tom Baker sat down near K-9 and began working on the Times crossword (Leeson's hobby), conversing with Leeson through the remote link. Without thinking about it, Leeson remained in character. He was later told that several young fans, who had come by to watch the production, were quite amazed by what appeared to be the Doctor and K-9 working on the puzzle together.
The interior sets for the hyperspace ship were made of wood. Normally, to avoid having the sound of the actors' footsteps sound like wooden thumping, would have required foleying (re-recording the footsteps on a different surface during post-production). In this case, however, the sound engineer put microphones under the floor and then electronically altered the sound so that the footsteps sounded (appropriately) like walking on a metal floor.
John Leeson (K-9) moonlighted at the time by taking photos of fellow actors for "Spotlight", an annual actors' casting directory. During production of "The Stones of Blood", he took several photos of Beatrix Lehmann (Professor Rumford), which she was quite pleased with. As a token of appreciation, she gave him a 1936 Leica camera that she had received from Sir Ralph Richardson. As of 2007, he still has the camera.
The cells on the Cessair's ship contain a dead Wirrn (The Ark in Space: Part One (1975)) and the "skeleton" of a Kraal android (The Android Invasion: Part One (1975)).
The exterior of the mansion and estate shown in the story were actually a business management school that was near the Rollright stone circle used for filming. One night, the TARDIS prop disappeared -- it had been trucked into the nearby village by students from the school.