The shoot for this episode was marred both by the weather (a problem that was to affect many episodes in this season) and by an unexpected visit from the police. Apparently they had received reports of a headless man sighted in the woods.
A bridge over the river Mole was used in the climactic scene. This bridge has since been demolished and new one built in its place.
This is one of only two episodes where the crew are seen outside the base on Xenon, the other being Power (1981).