According to John Barrymore's biographer, Gene Fowler, a few years after making this film, Barrymore bought a house in Hollywood for $6,000. He got the seller to lower the price to $5,000 by appearing for the closing in his Mr. Hyde makeup.
John Barrymore hauled many of his prized potted plants from his apartment to the set to appear in scenery in the movie.
Contrary to popular belief, this film was not shot at the Astoria Studios in Long Island. Principal photography took place between December 1919 and January 1920 in the rooftop auditorium of the Amsterdam Opera House on 44th St. in Manhattan, in order for John Barrymore to make his regularly scheduled Broadway appearances. In between February 1920 and September 1920, Paramount used the downstairs auditorium when it became available. The Astoria studios opened the following month.
Carew's line to Jekyll, "The only way to get rid of a temptation is to yield to it.", is not from the Robert Louis Stevenson story; rather it is a quotation attributed to Oscar Wilde.
In the short Renaissance flashback memory sequence, where Miss Gina is explaining to Hyde about the poisonous mysteries of her secret ring, set pieces and costumes were brought from "The Jest". That was a hit play in which John Barrymore had starred with brother Lionel Barrymore on Broadway in 1919 before shooting this picture.