At 1:11, the Curtis Turner character says "You have heard that Virginia is for Lovers, right?" The "Virginia is for Lovers" tagline for the Virginia tourism industry was not coined until 1969; approximately 25 years after the movie would have taken place.
At about 40 minutes in, when the two boys set out to race around the crude dirt oval, one of the interior shots shows a modern-day seat belt on the door post.