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.
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