The goof item below may give away important plot points.
Abraham Lincoln (shot 14 April 1865, died the next morning) says he is the final casualty of the Civil War. However, William T. Sherman's Union forces and Joseph E. Johnston's Confederate forces were engaged in battles in the Carolinas after Lincoln's assassination. The final skirmish of the war ended on 26 May 1865 when Confederate General E. Kirby Smith surrendered to Union General Edward R.S. Canby. (It could be argued that Lincoln, being dead, would not have known about those who died after him, or that he simply meant it in a metaphorical sense.)