The first blood transfusion of animal blood (sheep) to human was in 1667; the first successful transfusion of human blood was performed in 1818. Generally, early blood transfusions were risky and by the late 19th century had fallen out of favor within the medical field. ABO blood types were discovered in 1900; the concept did not exist in 1869.
Starting with this episode, John McIntire, Chris Hale, does not appear in the last four episodes of the series.
Melody Thomas Scott's first credited role.