You Have Just Been Murdered - S5-E21
Visible crew/equipment: Studio lights and reflectors can be seen in the Rolls Royce's shiny side panels as it backs up and leaves the alley. (00:26:00)
Visible crew/equipment: When Steed and Lord Melford find the lift out of order, shadows of the boom rigging and microphone make two separate appearances on the wall above their heads.
Visible crew/equipment: As Emma is leaving Steed's apartment, the boom dips into the shot at the upper left. (00:04:30)
Revealing mistake: The dead man in Steed's apartment is visibly breathing. (00:19:00)
Factual error: Major Robinson threatens Steed with a revolver equipped with a silencer. A military officer would certainly know better. Though it's a common movie and TV cliché, it is a glaring error. Revolvers are open-chambered, allowing sound to escape out the back of the barrel - so they can't be silenced. There are rare exceptions if the gun is heavily modified to close the open chamber gap, but that does not apply to the weapon featured here. (00:46:00)
Continuity mistake: The cigarette lighter Robinson uses to set the incriminating papers alight disappears from the desk as he makes his phone call. (00:21:30)
Visible crew/equipment: A large round studio light is visible in the lorry's door just after it strikes the motorcyclist. (00:02:00)
Quick-Quick Slow Death - S4-E19
Revealing mistake: When Mrs. Peel unmasks the recently-murdered Bernard, the corpse's eyelid twitches. (00:37:00)
Continuity mistake: Jackson plants an explosive device in the 12th green cup while Mrs. Peel is watching through the periscope. He doesn't pick it up again, but when Reed looks, Jackson is still holding the bomb. (00:44:00)
Continuity mistake: Georgie's wig, which she'd pulled off and placed over the flowers on the mirrored stand, either changes position or disappears altogether during Steed's fight with Ivanov. (00:40:55)
The Positive Negative Man - S5-E22
Continuity mistake: In the opening scene, Dr. Gray works at his drawing board while smoking a cigarette. From one shot to the next, as he looks up at the intruder, the cigarette disappears and he's smoking a pipe instead. (00:01:30)