Originally filmed November 8th to the 19th 1974 (18th episode in production order), but the episode ran short. New footage was added later, written by writer/Script Editor Johnny Byrne (filmed from February 25th to the 27th 1975, immediately after The Testament of Arkadia (1975) was finished shooting), including the scene with Dione in Sandra's quarters, as well as all scenes aboard Dione's spaceship. Scenes featuring a Bethan man, played by Alan Bennion, were deleted; Maxine Audley was hired as his replacement as Dione's superior Commissioner Theia. In addition, the originally-filmed ending was replaced, as the producers weren't satisfied with having Koenig simply giving Talos the coordinates of the Bethan gunship, sparing Alpha. A new ending was shot consisting of Koenig's sneaky ploy of taking matters into his own hands.
Reportedly, this episode's original story concept came from Barbara Bain, who suggested it to writer/director Bob Kellett, with the original idea being a "battle of the sexes", hence the original title "The Second Sex". Changes were made resulting in the temporary title "The Other Enemy", and the battle of the sexes concept was left vague.
During the show's opening credit sequence, the "This Episode" montage Includes shots of the remote-controlled laser tanks seen on The Infernal Machine (1976). This raises the possibility of a deleted scene in this episode involving the usage of stock footage of the tanks in one of the battle scenes (since the Eagles were unable to be launched).
Dione's escape craft was designed shaped like an egg; originally intended to have "dropped" out of the Satazius while it was still in flight.