During the car chase scene, the cars behind Quiller's Porsche appear and disappear, and are sometimes alongside his car, on the driver's (left) side.
When Quiller is being followed by the luxury vehicle on the highway, the shots of Quiller with the vehicle right behind him and the intervening shots of Quiller watching the vehicle behind him in his side view mirror are taken on two different stretches of road, the straight on shots on a relatively straight road, the mirror shots on a road with a wide curve.
When Hengel is following Quiller in their respective cars, Quiller, on a highway interchange on ramp, merges into traffic, with Hengel seen immediately behind him coming almost to a complete stop at the merge point to wait to merge. In the next close-up shot, Hengel is seen driving a good length of the on ramp again, not having to stop at all in order to merge.
During the car chase, Quiller looks in his rear view mirror at the accident behind him. The image is not reversed, as it should be in a mirror.
When they are together at the Olympic stadium Pol ironically offers Quiller ham who, true to his religion, refuses it. It is not clear whether this was a deliberate error on Pol's part.