Historical events in this episode place the action in a definite time frame. The Spanish-American War, which plays a pivotal role in the plot, was waged from April 25, 1898 to August 12, 1898. The Battle of San Juan Hill was fought on July 1, 1898.
Roosevelt's use of "National Guard" is questionable. New York, where he came from, did have one, but it didn't truly become "national" until 1903, well after this episode takes place.
The first of many episodes Judge Garth would be absent