Do Not Forsake Me Oh My Darling - S1-E13
Continuity mistake: When the Colonel enters Number 2's office/control room, the doors close as he comes down the ramp. In the next shot, however, the doors are still open.
Do Not Forsake Me Oh My Darling - S1-E13
Continuity mistake: Driving his Lotus through London, Number 6 passes a hearse. But when the shot cuts to a wider angle, the hearse disappears.
Do Not Forsake Me Oh My Darling - S1-E13
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.
Continuity mistake: Number 6 is sitting in jail rolling a cigarette. In the long shot, you can see that he's just exhaled a cloud of cigarette smoke. But, in the next shot, he has just finished rolling the cigarette and has yet to light it. (00:11:10)
Continuity mistake: Between shots, the bodies of both Kathy and the Kid change positions on the floor. Kathy's has moved away from the stairs, and the Kid's reverses directions.
Continuity mistake: In full shots, the judge's cigar is in his mouth. Every time a close-up is intercut, the cigar is in his hand.
Continuity mistake: Twice in this episode (once in the saloon and once in the sheriff's office), Number 6's coat is unbuttoned when he's inside, but has instantly buttoned itself up when he runs outside.
Continuity mistake: The drink Kathy brings the Kid changes positions on the table between takes. She places it on top of the small book, but it moves itself to the larger book, then back to the small one again, and so on.
Revealing mistake: When the red handkerchief is tied to Number 6's hand, Patrick McGoohan's wedding ring is visible in the close-up.
Continuity mistake: While Number 6 is being dragged behind the horse, a red bandanna tied around his hand disappears and reappears several times between shots.
Continuity mistake: While Number 6 is in the jail cell, he lights a cigar and starts blowing smoke. Just a few shots later, the smoke has vanished and he lights the cigar again.
Continuity mistake: At the final shoot-out, the Kid's hat lands and settles right next to his head after he falls. When Number 6 walks past him a few moments later, however, the hat has somehow moved itself more than a foot away.
Continuity mistake: The judge has two glasses in front of him on the bar. When the shot changes, there's just one glass.
Continuity mistake: In the saloon, between close-ups and cutting back to the master shot, the glasses in front of the men at the bar change positions repeatedly.
The Girl Who Was Death - S1-E15
Audio problem: For some reason, "Londonderry Air" was dubbed over the original song being performed by the actors/singers. Their lips aren't moving in sync with the words at all.
The Girl Who Was Death - S1-E15
Continuity mistake: When the bulldozer is on fire, the raging flames have died down completely in one shot, but are instantly burning brightly again in the next one.
The Girl Who Was Death - S1-E15
Continuity mistake: When Number 6 is trying to stop the rocket launch, the computer console in the center is emitting smoke in close-ups, but not in long shots.
The Girl Who Was Death - S1-E15
Continuity mistake: In the interior shot of Number 6 exiting the lighthouse, the red doors are open. When the shot cuts to an exterior view of him coming out, the doors are closed and he opens them again.
The Girl Who Was Death - S1-E15
Other mistake: When the girl makes her getaway in the helicopter and Number 6 emerges from the bushes and climbs aboard, look at the trees on the horizon as the helicopter takes off and supposedly lands later in another location. You can see that the helicopter takes off and lands in the same field. Also, the shot of Number 6 hiding behind bushes before jumping on the helicopter, and after climbing off it is the same one. It's from a slightly different angle the second time, but it's the same bush.
Deliberate mistake: The credits list "Number 86" as played by John Maxim. But no such character appears in the episode. Apparently, 86 was left on the cutting room floor, but the titles weren't altered accordingly.
Answer: It's even more obvious than you think, you know who number 1 is in the very first episode. When 2 replies to the question "who is #1?" Change the way he answers from you are number one (in the monotone or accented answer to, "You are, number 6. The comma gives you the answer. #6 is #1. It's the tone of the answer.