A lovely example of humor based on the country boy's ignorance comes when he tells his big brother Pete that Pearl Harbor is "across that Government reservoy up at Oxford." It's clear that in this remote part of the Deep South, not too many people have heard of Pearl Harbor. But in the wake of the Japanese attack, everyone now knows about it, even if they can't actually locate it on a map.
Another example comes when the little boy is at the recruiting station at Memphis, looking for his brother Pete. Although the boy is only eight years old and therefore way too young to join the army, he still wants to sign up. He shows his enthusiasm to the lieutenant by offering to chop wood and carry water, as they'll both be needed for cooking.
Finally, while the little boy is in Memphis he's taken home to have dinner with Colonel and Mrs. McKellogg. He shows his innocence by assuming that the apartment block is the McKelloggs' entire house and by describing the elevator as a "little room."