When Jack and Tom are walking home from the fishing trip, a truck passes them on the dark road. The same footage is used for before and after the truck passes them scene.
The African American boy doesn't have a baseball glove when the group of boys meet with Jack and Tom. When Tom encourages the group of boys to drop their gloves on the ground, the boy adds his too. The boy didn't go anywhere to get the glove, it just appeared on his hand.
Tom states that the Republic of China released fifteen American POWs in 1955. The People's Republic of China (Communist China) might have done so, but the Republic of China (Taiwan) has always been an American ally and would not have been holding any Americans prisoner to begin with.
In the movie, orange reflector squares are on the highway between the broken yellow painted lines. Those weren't used on the 2 lane highways until the early '80s.
When Jack is sunbathing in the backyard and is spotted by the lady neighbor, there is a shot with a plastic septic tank in the background. Back then septic tanks were made of concrete.
In one scene Gunny watches King Kong (1933) and is terrified by a scene in which Kong munches on one of the natives. That scene was deleted from the original theatrical release and not restored until the 1970s (Three Wishes takes place in 1955).
Set in 1955, Tom Holman enters a construction site with an orange warning sign. Prior to 1971, construction signs were yellow.
The mom calls the dog "Betty Jo" instead of Betty Jane when the dog jumps on the bed.