The Russian Grand Duke Alexei Alexandrovich visited the United States and was in the Midwest, arriving at Ft. McPherson on 13 January 1872. The buffalo hunt followed the next day, with Buffalo Bill Cody leading the party.
When this was made in the 1970's, it was nearing the peak of the Cold War with Russia, so having Russia as bad guys was a kind of novelty for Western audiences; however it's ridiculous since the real-life Russian hunting party situation was nothing like the one shown, whereas the Russians and the Indians got along splendidly.
First episode (which would continue for the rest of the series) where Fionnula Flanagan replaced Eva Marie Saint, the family mother, who dies off-screen in a barn fire (explained through exposition dialogue). Flanagan plays her sister, the kids' aunt, and is different in that she's rich and classy, struggling to become down-home and simple in order to help raise the daughters. Saint was probably overwhelmed by the thought of becoming part of an actual TV series since the first season is more of a comparably short miniseries than an episodic series.
Brian Keith would be no stranger to Russian story-lines. He speaks fluent Russian, and would later play a Russia leader in the disaster film Meteor and the TV-miniseries World War III.
Four character actors fit the roles they'd played for many years. Horst Buchholz as an overly-confident Russian usually played brash, disagreeable young men. Morgan Woodward played mysterious strong silent types. Cameron Mitchell as a seedy villain. Lloyd Bridges as a colorful, vibrant character. Mel Ferrer as an important crooked man. Brian Keith grouchy and determined. And last but not least, Christopher Lee as a sophisticated villain.