Singer Matt Monro's first and only film rôle. He picked the character as it was the smallest in the script; it was subsequently expanded once he was on board the project.
Filming started in April 1969.
This was one of those projects (along with Mister Kingstreet's War (1971) and Docteur Caraïbes (1973) of which Tippi Hedren later said: "Occasionally I accepted roles for the foreign travel involved." In "The Cats of Shambala", she called this movie "rather forgettable", while in her memoirs, published in 2016, she wrote: "I hadn't been home long from my second trip to Vietnam when I was offered the lead in a film called Satan's Harvest (1970). I was excited. Starring opposite George Montgomery was a lovely prospect, of course, and the script was fairly interesting, but mostly I was looking forward to shooting in South Africa, where I'd never been before."