[Note: The film drew parallels with an actual series of murders committed by a gunman (the so-called Zodiac serial-killer) in the San Francisco Bay area in the late 1960s.Yet he does advise Willie to stir up the indifferent voters, with different speech content:Look, Willie, you tell ""em too much.] The site of the race, the Circus Maximus in Jerusalem (Judea), was constructed on over 18 acres of backlot space at Cinecitta Studios outside Rome, and the filming of the sequence took about five weeks.Jonathan spoke privately to his conflicted son Clark, to express his concern and urge him to suppress his powers: "Clark, you have to keep this side of yourself a secret.