A Connecticut Yankee in King Arthur's Court
1952, directed by Franklin J. Schaffner
(IMDB Link) Summary from IMDB Comments: The Samuel Clemens (Mark Twain's real name) story transports a modern man from New England back a millennium and a half into the time of Arthur and Camelot. Culture-shock is just the tip of the iceberg. Often-copied and adapted, Connecticut Yankee is a classic 19th century farce.