Keith Alexander's (Lt. Ford) voice is dubbed by Robert Rietty throughout the entire episode. (Note: Alexander was unavailable for the episode's post-syncing).
Anthony Chinn (Alien) is one of 11 actors to appear in both Journey to the Far Side of the Sun (1969) and the UFO series. This was also his second episode, having previously appeared as 'Lt. Tony Chin' on Skydiver in Sub-Smash (1970).
Deleted scene: at the start of the episode, Jack Newton (the planned murder victim) is shown as having an on-going affair with his secretary.
The ending credits scene in the cemetery was unscripted.
Although Hugo Panczak (SHADO Mobile Navigator) also appeared previously as the captured 'Alien' on Computer Affair (1970), he received no credit for that episode.