Early drafts of the episode had Blake and Avon's roles switched round, with Blake leading the party on the planet surface and Avon staying on the ship and pursuing Orac in the next episode, Orac (1978). Their roles were swapped because it was considered inconceivable to have Avon meekly handing Orac over to Blake. Also, location filming for the previous episode Bounty (1978) conflicted with this one.
The Cephlon fertility cell rocket ship is a model of a Russian Soyuz.
From this episode, Avon wears a silver coat while teleporting down to planets instead of the colour-coded tracksuits worn by the other characters.
This is the first episode where the Federation's military is referred to as Space Command.