Continuity mistake: In the opening sequence, prior to the Prisoner being spirited away to the Village, the holiday photo inside his briefcase appears to turn 90 degrees between two quick edits.
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.
Plot hole: When Nadia had been held captive in The Village, how did she get word to her accomplice to be ready at the exact time, in the exact location, and with a packing crate ready, and a whole series of transports arranged? Even if Nadia was in on the ruse of conning Number 6, wouldn't he be suspicious?
Continuity mistake: An estate car can be seen crossing the background in one scene, as opposed to the village "taxis."
Revealing mistake: At the end of the episode when Number 6 and Number 2 are addressing the crowd, in the long shots facing 6 and 2 you can tell Number 2 has been replaced with a double. (00:47:51)
Visible crew/equipment: When Number 6 is hypnotising Number 86 with his wristwatch, as the camera moves in towards 86, you can see its shadow cast on 6's sleeve. (00:42:39)
Visible crew/equipment: At the end of the episode when Number 6 gives Number 2 the device and tells him to leave the island immediately you can see the shadow of the boom microphone on the stone wall behind them at the top right of the screen. (00:47:17)
Visible crew/equipment: Just before Number 6 and the woman break into her father's watch shop there is a shot of the shop's front door, as the camera moves in on the door you can see the face of the cameraman reflected in the door glass in the bottom right. (00:32:01)
Audio problem: During the scene when Number 6 warns Number 2 of a potential assassination attempt on him Number 2 brushes it off and says "it's the little watchmaker that concerns you" but his mouth does not match this. (00:29:43)
Revealing mistake: Obvious stunt double for Patrick McGoohan in some shots during his exercise routine. (00:11:53)
Revealing mistake: After Number 14 convinces Number 2 to let him deal with Number 6 both of them leave 2's office. As they do, you can see the "metal" on the doorframe has started to bubble. (00:30:57)
Continuity mistake: When Number 6 writes the coded message he uses black ink, after Number 2 intercepts the message it changes to blue ink. (00:37:24 - 00:38:30)
Visible crew/equipment: When Number 6 is listening to classical music in the listening booth, each time he puts his head into the booth (after switching records) there is a specific shot behind his shoulder where you can see the heads of two crew members reflected in the glass of the listening booth. This happens 3 times and is very visible on Blu-ray. (00:10:33)
Continuity mistake: Number 6 gets into the buggy with the hypnotised woman (Number 8, I think) however, when seen from behind, as the vehicle drives away, there is now only one person in the buggy. (00:29:47)
Visible crew/equipment: When Number 6 and Number 2 are observing the fate of "the rebel rook", who is being subjected to Pavlovian mind control treatment, there is a moment when the shadow of the boom microphone can be seen cast on the wall at the top-centre of the screen and bobs around for a while. When Number 6 says "you must be proud of yourself." (00:14:36)
Revealing mistake: When Number 6 finds the black cat outside his house you can see his shadow fall across the painted backdrop of the town behind him. (00:11:39)
Revealing mistake: When Number 6 is fighting the two smugglers on the deck of the boat you can see creases in what is supposed to be a foggy background.
Revealing mistake: On the raft, when Number 6 starts to take apart his radio, you can see that the raft is in very shallow water but it's supposed to be out at sea. (00:10:25)
The General - S1-E6
Visible crew/equipment: During the street party, when the interviewer asks Number 6 questions about European history, you can see a microphone in the bottom right of the screen. (00:28:08)
Visible crew/equipment: After uncovering the deception Number 6 enters his doppelgängers home to confront him. As the door opens you can see the shadow of a crew member on the wall next to the door. He is hidden behind the partition. (00:39:18)
Chosen answer: We were never told. In the series finale [Spoiler alert] Number 6 demands an answer to that question, only to be shown his own reflection.
Jean G