Extremely infamous German/Nazi Leader Adolf Hitler (along with Italian leader Benito Mussolini) is mentioned several times in this series (as well in footage used), but is never portrayed by an actor.
Though it was a major event, this series does not at all mention the assassination attempt made on Roosevelt's life (when he was President-elect) in February, 1933 in Florida. The attempt resulted in Chicago Mayor, Anton Cermak being slain.