Lifeforms native to Preplanis included the bloop, the bog monster, the bush creature, cyclamen, the cyclops, fish, the lost civilization, and the star, as well as many plants. The planet was also the home of an enigmatic non-corporeal being nicknamed 'Mr. Nobody'.
- Several online sources give the spelling of this world as "Priplanus". "Preplanis" is the spelling used at the Internet Movie Database. 
- Preplanis, which first appeared in The Derelict, was redesigned from the planet seen in the original pilot shot. Possibly this was to avoid any mistaking the world with Mars as occurred in No Place to Hide, although a reference to this was left in a later pilot scene edited into The Hungry Sea.
- Although the planet's destruction was never explicitly shown, the opening narration in Blast Off Into Space said "a cataclysmic explosion would rip apart the planet's core, and disintegrate their entire world - into galactic dust".