Two characters refer to "the Civil War," a Northern term that Southern contemporaries would not have used. Even at the time when this show was first aired, many Southerners still considered the name Civil War to be offensive and preferred to say War Between the States. It was only after social upheaval and cultural reevaluations in the late 1960s that the term Civil War began to be generally accepted in the South.
Contrary to what some people seem to have heard, Abraham Lincoln did not say, "I'm the last casualty of the Civil War." He said, "I guess you might say I'm the last casualty of the Civil War." He was speaking figuratively, not literally. He was implying not that he thought himself the last casualty, but that other folks might refer to him as the "last casualty," because of the shocking effect his assassination had on the general populace of the United States as the war was winding down, and the traumatic effect his murder had on those who held him in high regard for keeping the union together in spite of the divisive war.
The goof item below may give away important plot points.
Abraham Lincoln, who succumbed to his head wound on 15 April 1865, says he is the final casualty of the Civil War. However, William T. Sherman's Union forces and Joseph E. Johnston's Confederates engaged in battles in the Carolinas in late April after Abraham Lincoln's death, and a few Confederate pockets of resistance in still operated across Texas in May. According to official histories, a Union private named John Jefferson Williams, killed on 13 May 1865 near Brownsville, Texas, is acknowledged as the final casualty of the Civil War. (It could be argued that this story's Lincoln, being dead, would not have known about those who died after him, or that he simply meant it in a metaphorical sense.)