The original script had Alan Carter and Andy Johnson riding through the tunnel in the opening scene in a moon buggy. The filmed episode has them walking. Carter's "nonsense song" started out with "Moon buggy, moon buggy, travel in haste...", but since the vehicle was nowhere in sight, the word "moon buggy" was made inaudible on the soundtrack.
This episode was filmed simultaneously with The Rules of Luton (1976) (4 to 18 May 1976), which was why Martin Landau and Catherine Schell only appear in cameos. Although Season One had finished filming in February 1975, it took head of ITC Lew Grade until December of that year to finally give two thumbs up to the production of Season Two. In order to complete the filming for the season on schedule, two episodes were shot at the same time on three more occasions (The AB Chrysalis (1976)/Catacombs of the Moon (1976), Space Warp (1976)/A Matter of Balance (1976), and Dorzak (1977)/Devil's Planet (1977)). Season One had a three-week summer break from filming, but this season had no such luxury. Nick Tate pointed out that these "double-up" episodes suffered in quality due to not only each of these episodes containing little or no involvement from some of the cast, but because it's obvious that they were hastily shot.
Nick Tate later commented how producer Fred Freiberger (who was also Season Two's script editor) inserted nonsensical songs into some scripts for Carter to sing, and in this episode, also archaic terms into Alan Carter's dialog. "Bluey" was an old Australian nickname for a redhead, Carter's name for Andy Johnson. "Cobber", meaning close friend, which Carter uses as Etrec's nickname, was an obsolete term in Australia in the '70s, never mind in the 21st century, as Carter would most likely have simply used "mate".
The original script had the Alphans bust into Pasc's hijacked Eagle from the outside, but the budget wouldn't accommodate the construction of a life-size Eagle.
Reference is made to Krom II, a planet the Alphans had previously visited off-screen; the sign on the stasis chamber (which appears on both Pasc and Etrec's foreheads) was called "flammon", left by a godlike alien race (which may or may not have been the Archanons) as a warning of danger.