Producer Charles H. Schneer claimed that he chose this story after reading an article stating that Jules Verne's "Mysterious Island" was the most-looked-at book at public libraries.
The scenes on the island were actually filmed on the coast of Spain.
Although produced by different studios, it is obvious that the exterior design of the "Nautilus" submarine as seen in the film was heavily influenced by Harper Goff's "half crocodile/half shark" Nautilus design in Disney's 20000 Meilen unter dem Meer (1954), especially with respect to the sub's top spar and rounded "eye" windows. In the original Jules Verne novels of "20,000 Leagues Under the Sea" and "Mysterious Island", the Nautilus is described as being rather plain, basically a cigar-shaped steel tube with very little outside detailing.
This was the first film made in Europe by exiled director Cy Endfield to be released in his native USA with his name as director on the credits, instead of a friend's name or a pseudonym.
The opening scenes at the Confederate prison camp were shot in England and the exteriors were shot at Shepperton Square.