Trivia: The Manor to Penelope's right at the Clydeside launching of "Ocean Pioneer II" is Professor Holden from "The Mighty Atom". Tony Williams (from "Cry Wolf"), MI5 agent Tidman (from "The Man from MI5") and Lovegrove (from "The Vault of Death") are also visible in the crowd, as well as the Commander of "Ocean Pioneer I".
Trivia: In the opening scene, you can see two characters who have appeared in previous episodes. First, when the TV reporter comes through the crowd with the cameraman, you can see Blanche Carter (from "City of Fire") in the background, and the photographer who takes a picture of the impostor is Colonel Tim Casey from "Edge of Impact".
Trivia: This episode features the only appearance of a real human face in the series: when Lady Penelope peeps through a spyhole in the door of a bank during the opening scene. The face you see is that of puppet operator Judith Shutt, who was also Penelope's hand double throughout the series.