Revealing mistake: When Leslie is fighting the soldiers, one soldier hits a second soldier with his rifle. The rifle can be seen to bend around the soldier's body and then straighten again. (02:12:10)
Revealing mistake: As the Leslie Special nears Paris, shots of Natalie Wood in the passenger seat show no wind effects. The shots are rear projected and there is no motion in her hair or hat. Later in Paris her hat has changed and now blows in the wind.
Revealing mistake: In the shot of Prof Fate evading the Indians while heading into Boracho, the long view shots show his "smoke screen" encompassing the car. In the close ups (obvious blue screen type shot) there is no smoke in the car.
Revealing mistake: During a bar fight about 50 minutes through the film, loads of punches can be seen to miss their target. However the recipients always react as if they're hit.
Revealing mistake: In the final shot of the film the model makers neglected to include the antenna at the top of the Eiffel Tower, seen previously on the real tower in the establishing shot of Paris. (02:31:20 - 02:37:10)
Revealing mistake: The rock behind Tony Curtis while he is standing in his car to the left of him has a horizontal line across it where the two fake pieces fit together. (01:05:00)
Chosen answer: The cars and drivers were supposed to make the trip by ship from North America across the Bering Strait to a Russian port, where they would resume the race. As it happened, Leslie and Fate were stranded in a blizzard on the North American side before they reached the ship. The ice beneath their cars unexpectedly broke away and drifted across the Bering Strait, improbably arriving at the intended destination port in Russia. As they drift into port, we see Leslie's right-hand man, Hezekiah, waving at them from the Russian dock, which is only possible if Hezekiah made the journey by the very ship that Leslie and Fate missed.
Charles Austin Miller