This was the final episode to feature the opening "Mrs. Peel We're Needed!" tag scenes. Reportedly the American network wanted more room for commercials, so these usually extraneous sequences were eliminated.
The only episode where Steed and Mrs. Peel are played by two other actors: Freddie Jones as the former, and Patricia Haines as the latter.
Brian Clemens the producer of the series, told that during this episode Diana Rigg and Patrick McNee took some days off and that's the reason why the producers and screenwriters imagined a screenplay with some actors to replace them.
In the season's original viewing order, this is the first time the viewer sees the exterior of Steed's apartment building at Stable Mews in London.
Campbell Singer as Major B wears Royal Artillery uniform - his unit in WW2