Continuity mistake: When Seltzman is talking to Number 2, there's a chair beside the tea cart with a foot rest, visible in the shots from behind Number 2. But when the camera angle changes to Seltzman's POV, the same chair appears in the shot - without its foot rest.Jean G
Revealing mistake: When No. 6 is putting the 4 slides together to get the location information for Seltzman, as the slides are dropped into the top of the projector, they drop down the screen. However, a projector inverts slides, so they should slide up from the bottom. Also, when the last slide is dropped in, the final letters fade into view and not slide down as would be expected. (00:33:30)
Continuity mistake: There are many shots of The Colonel (whose mind has been switched with Number 6's mind) driving KAR 120C all around London. The footage is stock, shown in other episodes, and features either Number 6 or his stand in, but definitely not the Colonel.