Although the line-up of the "seven" changed considerably over the show's four seasons, the original characters envisioned by creator Terry Nation for the seven were: Kerr Avon, Vila Restal, Olag Gan, Jenna Stannis, Brell Klein, Tone Selman and Arco Trent (with Blake as their leader). They would all have joined Blake on the "Liberator" after their escape from the penal colony on Cygnus Alpha. However, subsequent rewrites, and budgetary restrictions, saw the characters of Klein, Selman and Arco being dropped (although Selman and Arco made short-lived appearences in the 3rd episode, "Cygnus Alpha") and replaced with Cally, Zen and later Orac (both computers, voiced by the same actor to reduce expenses).
Terry Nation had previously used a prison planet named Cygnus Alpha in his Doctor Who (1963) serial "The Daleks' Master Plan".
This episodes marks the first appearance of Zen, along with the Liberator handguns and teleport bracelets. The Liberator is referred to by name for the first time by Zen.
Federation Pursuit Ships are mentioned for the first time.