When Rusty is dancing in a lavender bodysuit, she wears high heels until about 2/3 way through and then she is shown with lavender ballet slippers.
In the "What'd I Say" dance number white tape or something similar appears and disappears from Lucky's right hand fingers.
About 15 seconds into Rusty's dance routine at the University of Nevada, the red-haired male dancer third from the left, wearing grey pants, white shoes and black socks, suddenly becomes a different person with blond hair, white pants, grey shoes and white socks.
Close ups of Lucky in his race car (at end, race) show his helmeted head a good way above the head protection roll bar behind him: in the rear view shots of his car, from other rivals P.o.V. helmeted head is clearly ('safely'!) within the head rest / safety roll bar curve.
When "The Coasters" first begin performing the song "The Climb," the close-up view shows none of them wearing glasses. When the camera zooms out to show the entire dance floor, the baritone/bass vocalist is wearing glasses.
While the Count and Lucky are under his car in the garage the Count is smoking a cigarette. And when they crawl out from under the car to greet Rusty, he puts the cigarette out on the floor. Even in those days when smoking was everywhere, nobody in his right mind would have a lit cigarette in a place full of oil, gasoline, and expensive cars.
During the race just after they pass the Nashville, Nevada saloon, the ground level camera crew in the median is clearly visible from the helicopter shot. This is not a case of improperly visible film equipment - right before the race begins the race announcer does mention that there will be TV camera locations all along the course.
In the dance/music scene on the "roulette wheel," Lucky is playing an electric guitar that is not plugged in.
The Count's (very expensive) Ferrari 250 GT suddenly transforms into a Daimler 250 SP Dart right before it crashes.
The roulette wheel dance floor is seen in two different clubs.
During the Viva Las Vegas dance/music sequence, even though it is already blatantly apparent, Elvis Presley is badly lip-syncing the lyrics.
At the Roulette Club, when Lucky sings "What'd I Say?", the piano on the soundtrack is a Rhodes-88 electric, but the piano on the stage is a baby grand acoustic.
During the auto race, the cars are supposed to be driving across the Hoover Dam from Nevada into Arizona. In reality, they are driving the wrong way across the dam, from Arizona into Nevada (where Las Vegas is); plus the race begins at night: the Hoover dam would be approximately 30+ minutes (standard) driving from Las Vegas, but the race cars are shown crossing in (early morning?) daylight.
There are no Marinas near Hoover Dam. The helicopter would have flown for a few minutes before they would have seen one.
Lucky claims that he built his race car himself. The car is actually an English built Maserati with its steering on the right side. If Lucky had built his own car he would've put the steering on the left as all American cars have.
In the lead-up to the song "The Yellow Rose of Texas", Lucky Jackson names three exemplary Texans - Sam Houston, Davy Crockett, and John Wayne. None of these three were actually native Texans, and only Houston lived there for any length of time, serving as President of independent Texas and later Governor of American Texas. While Crockett figured prominently in the struggle to gain Texas' independence from Mexico in the 1830s, Wayne's only connection to Texas was making movies set there.
Finish line. Right side. One of the movie extras starts to cross the street but doubles back when the cars turn the close corner.