The climax involves an escape attempt via helicopter. The craft acquired for this episode was a different type from those used in the main location shoot at Portmeirion. Unfortunately, a stock shot of one of those was inserted in the sequence, its clear-bubble cabin and pontooned landing gear contrasting with the paneled cabin and naked struts of its fellow in the surrounding footage.
When #6 meets his double, they box and #6 falls backward onto a muddy street. Seconds later, the back of his jacket and pants are clean.
The final act opens with an exterior shot of Number Six's residence, even though Number Six is inside Number Twelve's dwelling.
At the end of Ep.1.4 (The Schizoid Man), No 6 leaves on a helicopter and, after his trip is canceled, lands back in the village on a different one (fitted with pontoons)
Toward the end the helicopter seen on the ground is an SE-3130 Alouette II c/n 1210 bearing registration F-BOEH, but seen in the air it is Alouette II SE-3130 c/n 1203 bearing registration F-BKNZ presumably stock footage from "Arrival" and also has floats on the skids whereas the former does not.
During the first conversation between Number 12 and Number 6, the cigar smoke vanishes along the line that marks the boundary between the two exposures that were made to achieve the doppelganger effect.
During the sequence when the Prisoner is discovering the deception, he sits down on the sofa next to the table lamp. There seems to be some trouble with the lighting, as a key light appears to have gone dim, and some ratcheting sounds are heard which are probably due to another light being aimed to cover the partially lit area.
Early in the episode, when the electric door opens in Number 6's house, it goes too far and bumps into the bookcase behind it, making an audible clunk.
At times when #12 and #6 are on the screen at the same time a line can be seen between them and the images used to make the split screen jitter slightly against each other.
When the two Number Sixes are preparing for their pistol duel, the shadow of the Number Six in the white suit falls across the split screen used to double Patrick McGoohan. At first, the shadow of his head is missing, then it comes in slightly out of sync with the rest of his shadow.