In this episode it is explained that a time differential exists between Thel and Earth; for every year that passes on Earth roughly 10 years pass on Thel. Princess Metra aka Kelly Bradford was transported to Thel in the 1960's but ruled the Metraplex province nearly 200 years ago.
Last show of the series.
The scene where Captain Valdor saves Gina (as Princess Metra) from an assassin contains a box with a Garth Chemical logo. This same box also appeared in the premier episode of the CBS show Whiz Kids ("Programmed for Murder", airing October 5, 1983).