The color master tapes of this seven-part serial were wiped by the BBC in the 1970s and it only held 16mm black and white telerecordings. However, in 1985 NTSC color tapes were recovered from TV Ontario in Canada and converted back to PAL for British broadcast.
Originally SGT Benton role was to be a nameless SGT, however Directer Douglass Camfield decided to make the role Benton to allow his Protege John Levene to expand his acting career, this combined with Previous producer Derick Sherwin's suggestion that the 1970 series feature Benton, both of these factors led to Levene receiving a regular contract for the following year.
Christopher Benjamin is one of 39 actors to have acted in both Doctor Who (1963) and Doctor Who (2005).
Voted by fans as the ninth greatest Doctor Who (1963) serial in Outpost Gallifrey's poll in 2003 to celebrate 40 years of the series.