In the studio shots in the trading company office, Steed has a large green smear across the back of his suit. In all the external shots, the smear disappears, but it reappears when he returns to the office.
When Merlin detonates a sleeping gas bomb early in the episode, he, Steed and Tara all sleep for a whole day. Yet when he detonates another bomb toward the end that puts both Hearn and Tara to sleep, she wakes up only a short time later.
When Jenny shows Steed and Merlin the news footage of Brigadier Hansing, for a brief moment the blue frame around the TV screen disappears, revealing it to be a projected image rather than an actual monitor.
An extreme close up of Brian Blessed's face (as Sergeant Hearn) reveals the underlying gauze on which the hair of his obviously false moustache is attached.
When Steed and Merlin view the news footage from the monitor in the transmitter van of the town's evacuation, the style of vehicles shown clearly depicts a scene from a much older era.
Shadow of boom microphone visible on wall when Merlin is introduced to Tara.
Shadow of boom microphone visible on wall during final scene in Steed's apartment.