One interesting thing is the theme music played as the KKK rides around killing blacks and other republicans. It was ‘The Ride of the Valkyries’ from Wagner’s ‘Die Valkyrie’. Obviously they did not know in 1915 about the German regime 20 years in the future that treasured Wagner and this music.
Wagner himself was a racialist of some form, which may be related to its use in the film.
It’s a pioneering movie and an impressive bit of progressive propaganda, up there with Triumph of the Will.