In the first flash-back scene, the Confederate soldiers arrive at the Big House carrying a red flag with a blue x with white stars. This is a "Jack flag" it is NOT the flag if the CSA. It is a battle flag for some particular unit in Tennessee during the Civil War (& it is possible these soldiers are from that unit; however, they would not have just the battle flag without their national flag.)
In modern days, this red flag with blue x and white stars has incorrectly been identified as THE Confederate flag.
The Confederate flag is white with the upper left corner being red with a blue x and having white stars in it.
According to the opening credits, the movie takes place in February 1962. The reporter, Quentin, emerges from the airport and climbs into a 1963 Ford. That vehicle didn't yet exist.
During the wide shot of the plantation, a moving station wagon is visible in the back.