Revealing mistake: As Machine Gun Joe runs slowly runs over a fisherman in a small brook, he stops and "peels out" on his head. You can see a film crewman in the driver's seat doing the actual carnage.
Revealing mistake: You can see the threads moving the submarine underwater. (00:04:55)
Revealing mistake: Anytime there is a fight, the hits hardly come close to making contact, but the sound effect is still there.
Revealing mistake: When Clint Eastwood is at his Sanction in Zurich, he climbs up a drain pipe, and climbs through a window, if you look behind him, you can see a rope. (00:19:40)
Revealing mistake: There are two actual games played out: one in Huston and one in Tokyo - the score board has identical faulty light bulbs in both locations.
Revealing mistake: During the chase sequence towards the end of the film, Roger shoots five bullets into the windscreen of the blue car. If you look carefully, you can see there is no driver in the front seat.
Revealing mistake: When the black guy is attacked after being let go, his throat is slashed. Check out how dreadfully fake the blood is. It looks like watered down ketchup.