At the completion of the opening credits, when the view switches to the wide shot of the pack preparing to make a left turn, the lead bike (Johnny) already has the trophy tied to the headlight. Johnny isn't presented with the stolen trophy until a later scene at the races.
Gil Stratton's motorcycle changes from a Triumph from when he leaves the races to a Matchless when he arrives in Wrightsville.
When being chased by townsfolk, Johnny hides behind a wall. A total shot shows him back-to-wall until the chasers have passed. In the following shot, he has turned by 90 degrees to the left and stands clear off the wall.
The mark on Johnny's face (below left eye and received in earlier fight with Chino) is missing in the motorcycle ride to park with Kathie but shows up later in following scenes.
In the first hour of the movie it is obvious the town's main streets are made of dirt and unpaved. Later, when Kathy is fleeing from the motorcyclists, and after she returns with Johnny, the streets are paved.
The jukebox in Bleeker's is extremely loud, with selections of hot jazz. This would not be acceptable for public tastes in such a small, old fashioned town.
About an hour into the film, when Johnny and Kathie are talking in the woods, she's leaning against the exhaust pipe and he's leaning against the muffler. Both of those surfaces would have been far too hot to touch.
Obvious stunt double for Johnny when he jumps a fence, just before getting back to his bike.
Obvious stunt double for Johnny when he and Chino are fighting - his hair changes from short and blond to longer and black.
Wire holding handle-bar/throttle can be seen during side view of Johnny's run-away cycle before it hits and kills Jimmy.
When Johnny knocks Chino through the window of the clothing shop, it is obvious that there is no glass in the window, only balsa wood mullions (i.e., the bars between panes of a multi-pane window).