When Charles is seeing Willa in St. Louis and eating in the restaurant, they go for a walk and then returning to the restaurant. During the walk, Charles' rank is Corporal. Back in the restaurant, his rank is much higher, that of a First Sergeant. When he leaves, he is a Corporal again. Later in the same episode, Charles and Willa are dining at the same restaurant, when he is confronted by his superior & enemy, Captain Venable, who acknowledges Charles has been promoted to Sergeant.
Orry Jr. was born during war. Series takes place 5 years after the war ended. Still he is only about 1-2 years old.
On the other hand, Gus, son of Charles Main, is 5. They should be around the same age.
It's obvious that the remaining facade of Mont Royal is not actually set at Boone Hall which was the filming location for Mont Royal in the first two books. There are old buildings along the road near the main house that are not present in the previous episodes and the long rows of oaks are not present either.
The call of a common loon is heard with location given as Richmond, VA where the common loon is not found during a time of year it would be calling. Further, the sound of the Eastern Whip-poor-will is heard during the broad daylight. Eastern Whip-poor-wills only call at night.