Continuity mistake: While the gunrunner is untying the raft, he's holding a half-eaten green apple in one hand that wasn't there in the previous shot. It disappears again as the raft floats away. Then it comes back - but it has now become a red apple instead of a green one.
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.
Continuity mistake: When Number 6 jumps from the gunrunners' boat, he's on the starboard (right) side. In the next shot, though, the bad guy shoots at him from the boat's port (left) side. (00:20:30)
Continuity mistake: The windows in Number 6's flat are curved on the inside (as is the wall). But on the outside, the windows are flush against a flat wall.
Continuity mistake: Mrs. Butterworth has a sandwich plate in her left hand and her cigarette in her right - until the shot cuts, at which point the cigarette and the sandwiches have instantly changed to the opposite hands.
Chosen answer: We're led to believe Rover is some kind of robot in the series. According to books on the show, Patrick McGoohan was looking for an unusual guardian for the Village, looked up at the sky, and saw a weather balloon, which was what Rover was.
Captain Defenestrator