As Carol leaves the gazebo after Edwina arrives, she has to run a good distance to get to the tree where the blue rag is kept to alert patrols to "yanks", but when McB hears horses, he can see the front gate from the gazebo.
When Carol leaves the house to find McB, she spots him in the gazebo playing cards. He is laying out the cards with his right hand, but when the camera angle changes to show Carol arrive, he is laying out the cards with his left hand.
The mushrooms that Pamelyn Ferdin's character gathers are Portobello mushrooms. These are a species that grow in open fields and lawns, not in shaded woodlands.
The turtle bounces like it's made of rubber.
When McBurney is playing cards, the deck has both the symbols (hearts, spades, etc) and the number in the corner. Numbers were not printed on cards until 1864 and it was extremely rare to see a deck with them until 20-30 years after the war.
Edwina sings a couple of lines from the gospel song "In the Garden", which wasn't written until 1912, more than 50 years after the time period of the story.
When his character is introduced McBurney claims to be a Quaker, but then later he pours himself some wine. Quakers do not drink alcohol.
Civil War-era Clint Eastwood has a very 1970 hair cut, complete with mutton chops.
In the opening scene (c. 3 minutes) the little girl doesn't actually pick the mushrooms, she just gathers up previously picked (and very clean) fungi by their cups. To pick a mushroom in the wild one must grasp it at the bottom of the stem or use a knife. Picking a mushroom by grasping the cup would break it in two.