Frazer Hines was on a scheduled break during the last episode but did appear in a pre-recorded film insert at the conclusion.
This episode was watched by 7 million viewers on its original transmission.
Benton's role in this episode was written for SGT Walters played by James ThornHill, but he became unavailable for the recording, and as such Douglass Camfield decided to give the lines to Benton so as to further John Levine's acting career.