This is a "bottle episode" defined as a budget saver with most of the action on one set, limited number of cast, and no filming on location.
Anthony Chinn (Lt. Tony Chin) is one of 11 actors to appear in both Journey to the Far Side of the Sun (1969) and the UFO series. This was his first episode, appearing later as the 'Alien' in The Square Triangle (1970).
Burnell Tucker (Albatross Pilot Turner) appeared in several sci-fiction TV series and films, including the roles of 'TMA-1 Site Photographer' in 2001: A Space Odyssey (1968) and as a Rebel Officer in two Star Wars movies.
At 46m 18s Straker tells Nina she will soon be back on Moonbase. This whole story was based aboard Skydiver.
However - "Nina Barry, normally a Moonbase operative (and later Moonbase Commander), briefly served as communications officer" (on Skydiver)
This was the final episode filmed at the MGM British Studios in Borehamwood. The rest of the series was produced at Pinewood Studios without some of the original cast (such as George Sewell (Col. Alec Freeman), Gabrielle Drake (Lt. Gay Ellis), Antonia Ellis (Lt. Joan Harrington), and Keith Alexander (Lt. Keith Ford)).