Visible crew/equipment: When Number 2 and Number 6 are talking at the beach there is a shot of Nadia getting into the sea. Just before she takes her sunglasses off you can see rows of spotlights reflected in them. This is because the scene was shot in a studio and not a real beach. (00:15:25)
Other mistake: When No.8 has been caught by "Rover" in the sea, she is pulled back unconscious to land by one large Rover and 2 smaller Rovers (one on each arm). Her legs are seen to kick (swimming style) to help them move. (00:17:25)
Visible crew/equipment: When the unconscious body of Nadia is being dragged onto the beach by Rover you can see the distinct shadows of two crew members and the camera being cast on the ground. (00:18:06)
Visible crew/equipment: When Number 6 meets Number 2 at the hospital, the shadow of the boom microphone is visible moving around at the top of the screen (on the wall), just before Number 2 greets him. (00:18:53)
Revealing mistake: When Number 2 and Nadia are in the box, the illusion that they are separated is broken by the edge of Number 2's blanket (and it's shadow) curling round into Nadia's side. (00:39:16)
Continuity mistake: Number 6 chooses a rather thin tree to cut down and fashion into his canoe. Somehow, when he's finished hewing out the wood to form the boat, it's considerably wider than the tree he started with.
Continuity mistake: After Nadia and Number 6 are placed into the packing crate, there's a shipping label on the front. In the next shot, it's vanished. Later, it reappears, but is now on the crate's side.
Continuity mistake: Due to a very poor edit, an extra walking past Number 2 and Number 6 as they talk on the patio disappears in mid-shot.
Revealing mistake: The "metal" door frame in Number 2's office is bubbling and peeling away from the wall.
Revealing mistake: When Nadia and Number 6 are embracing, many of the reverse-angle shots showing them from behind betray the use of a double for Nadia. Nearly every time the camera angle changes, she is noticeably several inches shorter.
Factual error: The truck transporting Number 6 and Nadia drives on the left side of the road. Fine for England, where the scene was shot - but they're supposed to be in Poland, where everyone drives on the right.
Continuity mistake: Nadia's number badge is upside down when she serves Number 6 breakfast. It's turned itself right-side up when she leaves, though.
Continuity mistake: In long shots of the truck transporting Number 6 and Nadia, the crate they're supposed to be hidden in disappears from the truck bed.
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.
Continuity mistake: Number 2 sits down and places his umbrella beside him with the handle facing out. The camera angle changes, and although he hasn't touched it again, the umbrella handle is now facing inward.
Continuity mistake: When he's playing chess with The General, Number 6's jacket changes between takes. At first it has solid piping on the lapels, then the piping has gaps, then it doesn't again.
Continuity mistake: When Number 6 and Nadia get into the shipping crate, they're both able to stretch out completely for the 12-hour trip. But when the crate is opened, it's suddenly several inches shorter, and 6 has to bend his neck at an uncomfortably sharp angle to fit into it.
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?
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