Several key cast and crew members watched the original broadcast in a random person's living room. The group was being driven through Surrey for an evening shoot for an upcoming serial (Seeds of Doom) when Elisabeth Sladen pointed out to Tom Baker that it was about airtime for this and it would be the first one of hers that she wouldn't be able to see. Tom pointed out that they could probably knock on a random person's door and ask to watch themselves on television. Elisabeth was amused by this, but Tom had the driver stop and in fact knocked on a door and politely asked the homeowner if the group could watch Doctor Who with them.
The Doctor says to Sarah, "Listen, once upon a time, there were three sisters, and they lived in the bottom of a treacle well. Their names are Olga, Masha, and Irina." This is a mash-up of lines from Lewis Carroll's "Alice in Wonderland" and Anton Chekhov's "Tre sestry."
Terry Nation envisaged the Kraals as somewhat insectoid in appearance, although this idea was not used in the design work.
This episode was watched by 12.1 million viewers on its original transmission.