Although the title of the film is "A Connecticut Yankee", this was not a film version of the 1927 Rodgers and Hart musical, which was also based on the Mark Twain novel. In fact, this film was not a musical at all and did not use the Rodgers and Hart score, not even as background music. The Rodgers and Hart version was never filmed.
Some sources erroneously reverse the roles played by Mitchell Harris and Brandon Hurst. Harris plays Sagramor and the Butler and Hurst plays Merlin and the Doctor.
The name of Roger of Claremore, who Hank says was his ancestor, was an inside joking reference to Will Rogers himself, who was born in Claremore, Oklahoma.
Version presently available, and the one shown on Turner Classic Movies in December 2010, is the 1936 re-release, with a Twentieth Century-Fox logo, redesigned opening and closing credits, and original exit music eliminated. Shorter running time indicates that some editing had also been done, most likely in order to meet Production Code demands which were not in effect at the time of the film's original release.