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.
Continuity mistake: Watch when Jack Lemmon falls into the giant cake at the beginning of the pie fight scene: he destroys all but a thin vertical pillar on the right side. During the fight, we see two other angles on it before the cake is fallen on again - in a shot from the exact same angle as before - but this time a large portion of it has somehow restored itself, and in a completely different configuration.
Audio problem: In the beach scene near the beginning, Leslie Special comes to a screeching halt in front of Leslie's tent on a bed of sand. Can't burn rubber there.
Factual error: When the race starts, the people are waving American flags with 48 stars: 6 rows of 8 stars each. However, in 1908, when the race took place, there were only 46 states.
Audio problem: Throughout the pie fight and more noticeable in the first minute of it, when it's relatively quiet, the production photographer's motorized camera can be heard just before and after each pie is thrown.
Continuity mistake: As the bakers assist the Prince to get out of the cake he's fallen into, the General begins to descend the stairs to the kitchen. Yet the general is not seen again until just before the Prince hits him with a pie.
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