Clemens was actually a deserter from a Confederate militia company in his home town area of Missouri in 1861. It was the basis of his story "The Short History of a Private Campaign That Failed".
The scene where Clemens receives an honorary degree from Oxford University in 1907 was the recreation of an event that C. Aubrey Smith, who plays the Oxford Chancellor, actually witnessed.
Filming Location: The riverboat scenes were most likely filmed on the Sacramento River.
Footage of the riverboats was later used in the Warner Brothers TV series Maverick (1957).
The typesetting machine (aka Paige Compositor) for which Clemens was so enthusiastic was never a profitable venture due to the need for continual adjustment. Clemens' investment was about $300,000 or in present day monies: $5,820,000.