Because this episode ran short, the closing moments were augmented with the subplot about the overloading motive units. The cliffhanger had originally centred on Zilda's death.
Tom Baker disliked the scene where SV7 rescues the Doctor from being buried alive. He suggested an action-packed sequence in which the Doctor swings on his scarf to kick the door open. He and Michael E. Briant argued vociferously until Briant revealed that Graham Williams was present to observe the shoot. Baker quickly agreed to follow the director's instructions.
This episode was watched by 12.4 million viewers on its original transmission.
This episode takes place on Storm Mine 4 in the 23rd Century.