Continuity mistake: Paul Newman and the Count are in the car heading to the rehearsals. When they are about to arrive, the background behind the Count shows a pier, but when the angle changes the background behind Newman shows the car surrounded by buildings.
Continuity mistake: When James Coburn is about to leave the phone booth where he's been lighting matches, the number of matches he leaves on the top of the phone changes between shots.
Continuity mistake: Adrian and Le Borg are flying on a modern-day commercial jet. Just after the explosion, there's a quick aerial shot of the plane plunging from the sky. However, the airplane in the scene is definitely not a jet, as seen by the shape of the wings. This appears to be stock WWII film footage of a military fighter plane that was shot down.