When Miss Martha walks down the steps to answer the door, she is initially seen holding a revolver in her left hand. Then suddenly before she gets to the door, the revolver is in her right hand.
Miss Martha asks for and receives cartridges for her pistol from a passing Confederate officer. Her pistol is an 1848 Colt Dragoon percussion pistol, loaded separately with powder, ball and percussion cap, not a contained cartridge.
Palmettoes and Spanish moss don't grow in Virginia. Roses and vegetables aren't grown in the shade.
The scenes of the plantation contain Live Oaks, which are particularly noteworthy when presented with the plantation's Oak Alley. But in Virginia Live Oak only grows in the southeast, where there was no fighting in 1864. In 1864, there was fighting in the Shenandoah Valley, as well as in Grant's Overland Campaign (which took place from the Fredericksburg area down to Petersburg). Live Oak does NOT grow in these areas of Virginia.
Corporal McBurney sets about sharpening a tool on a whetstone wheel in the garden during his rehabilitation. However, he spins the wheel towards himself as he begins to get it going. This is incorrect. The wheel should be spun away from the user, so that the tool "skims" over the surface, and doesn't have a chance of digging into the wheel and jamming the tool into the user.
Twice, both times during dinner, Miss Martha makes the Sign of the Cross incorrectly - she crosses from her right shoulder to her left shoulder instead of vice verse.