When Burt Munro and the Air Force guy make the left turn onto the salt flats, we see in the background the double-ended arrow indicating that the road ends and drivers must make a right or left turn. Below the double-ended arrow, we can see iconic angle arrows also pointing left and right. Arrows of this type were not introduced onto the roads until the mid-1980s.
When Burt Munro arrives at the Flamingo Hotel and is thumbing through his money to pay the cab fare, his dollar bill is clearly a Federal Reserve Note and not the silver certificate at the time. If it was important enough to show the scene, it should have been important enough to know and procure the right generation of currency. Federal Reserve Notes were not in existence until as the silver certificates were being retired, in the later 1960s.
Very early in the movie when Burt Munro drives to town to meet Sarah to ask her out, there are parking meters clearly visible outside the building. There were no parking meters in New Zealand in the 60's.
In the bar on the way to Bonneville, the waitress offers Burt Munro his choice of beers-including Coors. At the time depicted in the movie Coors was not readily available outside of Colorado, if at all.
In the movie, the nickname of one of Burt Munro's friends is mispronounced. The friend's nickname was "Rollie". In the movie this is pronounced to rhyme with "jolly", but in real life the nickname rhymed with "holy".
In the final scene when Burt Munro unlocks the paddle lock so that he can slide the bolt to the left to open the door, the bolt was already in the unlocked position. The clasp of the paddle lock needs to go through the bracket at the end of the bolt AND the bracket directly above it if you want to lock the bolt in the closed position so that the door can not be opened.
When Burt Munro is racing the group of young guys towards the beginning he has on a dark tan tinted pair of goggles. But when he wrecks his bike around the turn and stands up, he has on white non-tinted goggles.
When Burt's motorcycle and trailer break loose from his car at high speed, the trailer upsets on the gravel covering the shoulder of the road, settling on the left side of the motorcycle. Yet when the bike and trailer are righted there is no "road rash" or damage of any kind on the left side of the cycle's fairing.
Burt Munro was born March 25. The character in the movie celebrates a birthday party 5 days before leaving New Zealand. Speed Week at Bonneville is in August. It takes 21 days for a ship leaving New Zealand to reach Long Beach in California, and 11 hours to drive from Los Angeles to Bonneville in Utah. It leaves one to imply that the movie begins in late June/early July.
At the beginning of the movie the young neighbor who has boiled the kettle for Burt's tea takes the kettle directly from the stove and without oven gloves or a cloth to absorb the heat. The kettle would have been extremely hot through conduction and could not be handled without thermal protection.