The music being played at the party/ball is Johann Strauss. The piece was first performed in 1867; after the Civil War ended.
During the battle scenes, the Confederate and Union infantry advance in open order like World War 2 infantry, not in lines like infantry of the Civl War era.
When the Confederates are trying to round up the horses Confederate cavalry wore yellow banding around the collar and sleeves not blue. Infantry wore blue and artillery wore red.
The real General Braxton Bragg wore a beard.
At approximately 1 hr 09 min and 1:hr 10 min, the exact same scene, where a cannon ball explodes next to two horses running away from the camera and the soldiers fall off their mounts, is repeated.
Brenda Scott's hairdo was a "That Girl" Marlo Thomas replica circa 1968. No woman on earth wore that hair style in 1862.
The rifles everyone carries are Springfield Trapdoor models, which weren't made until 1879, 14 years after the Civil War ended.
Actually the Trapdoor Springfield was introduced in 1865 as a conversion for old muzzle loaders. The .45 caliber Springfield was introduced in 1873.
Actually the Trapdoor Springfield was introduced in 1865 as a conversion for old muzzle loaders. The .45 caliber Springfield was introduced in 1873.
J.C. threatens the others with an 1873 Colt Revolver when he wants to leave the group.
James Caan's hair, like that of some other characters, is an obvious wig.
The background at Corinth (prior to the hospital scene) is an obvious matte painting.