Continuity mistake: When Number 6 falls on the beach, the sand under him is wet. In the next shot, it is obviously dry.
Continuity mistake: The towel in Number 6's locker changes colors. When we first see the locker opened, the towel is white. A few shots later, when it's opened again, the folded towel has turned blue.
Continuity mistake: Rover herds the boat back to the beach, and several people who were aboard minutes before (some of them unconscious) have somehow disappeared from its decks.
Continuity mistake: Alison is thanking Number 6 for letting her practice on him. In close-ups, her hands are at her sides. But in longer shots, she has her hands folded under her chin.
Continuity mistake: In the court room scene, Number 6 has wind-blown hair in the master shot, but is nicely combed up and neat in all the close-ups.
The General - S1-E6
Continuity mistake: Number 6 holds the Penny Farthing pass in both hands in close-ups, but in all the master shots, he has it in just one hand.
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 they're "playing" on the swing, Number 6 has his hands on the Butler's shoulders, and the Butler is wearing gloves - yet there's a close-up of someone's bare hand holding the rope.
Continuity mistake: Nadia and Number 6 go together to the Green Dome (Number 2's residence). While they stand at the entrance, the door knocker changes to one of a completely different design between one shot and the next.
Visible crew/equipment: Watch the bottom left corner of the screen when Rover turns around and begins pushing Number 6 away from the helicopter. A film crewmember's head (probably that of the technician operating the weather balloon that played Rover) appears briefly in the shot.
Do Not Forsake Me Oh My Darling - S1-E13
Continuity mistake: Number 6 pulls up to his London flat and there are six cars parked across the street. When he gets out just seconds later, there are only two cars parked across the street.
Do Not Forsake Me Oh My Darling - S1-E13
Continuity mistake: The configuration of the photos on display in the camera shop changes completely from one angle to the next, depending on whether the camera view is from the outside looking through the window, or from the inside looking out.
Continuity mistake: During their kosho match, Number 6 ends up dangling Number 14 over the water. In the first shot, he's holding the man with his left hand. In the next, he's using his right hand.
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.
The General - S1-E6
Factual error: When Number 6 types "WHY?" on the typewriter, the sheet of paper comes out with the word centered on the page. But the typewriter's carriage was pushed all the way to one end, so the word couldn't possibly have wound up in the page center.
The General - S1-E6
Continuity mistake: At the end, using only one finger of one hand, Number 6 types 4 characters on the typewriter. He then expressly states that what he typed was, "W-h-y question mark." But you can't type the question mark with one finger: it requires holding down the shift key.
A. B. and C. - S1-E3
Continuity mistake: Number 14 has to push a button to activate the first tape she puts into the player. She then puts on the 'A' tape and it starts playing by itself, with no button pushed. When she puts in 'B,' though, she has to push the button again.
Continuity mistake: The council members' signs keep changing during the "Dem Bones" sequence. "Entertainment" becomes "Anarchists" and several others switch places between cuts.
Continuity mistake: One of the bad guys prepares a tea tray in the boat's galley and carries it up to the bridge. Throughout his preparations and his trip up the stairs to the upper deck, the contents of the tray keeps changing. The items rearrange themselves, and the size and shape of the bread loaf alternates several times.
Revealing mistake: In the aerial shot from the helicopter as it overflies the Village, another "real world" car can be spotted parked next to the Green Dome.
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.