Actor Cody Piper, who plays the lead role of Johnny in the film, was discovered in his home town of New Richmond, Ohio while playing on the local baseball team for his school. He was chosen over others due to the similarity between Piper and the original Johnny Clem in photographs.
Johnny was filmed in seven different states over the course of nearly two years - Ohio, Indiana, Kentucky, Georgia, Virginia, Maryland, West Virginia, as well as the District of Columbia.
All sketches and drawing used in the film are originals taken from the pages of "Harper's Weekly", a popular newspaper of the era.