Kevin Lindsay found the Sontaran costume very demanding to wear. His discomfort was exacerbated by a heart condition which would result in his death just six months later.
Tom Baker broke his collar bone while taping part 2 of the serial. it lead to stuntman Terry Walsh having to double Baker in a number of scenes.
This episode was watched by 10.5 million viewers on its original transmission.
A sequence in which the Doctor and Harry meet and hear Sarah Jane screaming had to be abandoned due to Tom Baker's injury.
This episode takes place on Earth in 16087.