For years this was regarded as a "lost film" with no prints or elements known to exist. A nitrate release print was discovered in the Czech National Archives in Prague. This print was a subtitled edited version that was in poor condition and contained numerous splices. Years later, a print of the uncut British version was finally discovered.
Some U.S. theatre prints were shown in spherical widescreen. The movie wasn't shot in widescreen. The bottom of the screen had been matted to cover up the Czech subtitles (present on the only known existing version at the time) thereby creating the rectangular widescreen shape.
When Boris Karloff traveled to England to shoot The Ghoul (1933), it was the first time in nearly 25 years that he returned to his home country and reunited with the surviving members of his family. Filmed March 13-late April 1933, it was Karloff's first British feature (his last would be "Curse of the Crimson Altar" in 1968).
The failure of the original copyright holder to renew the film's copyright resulted in it falling into public domain, meaning that virtually anyone could duplicate and sell a VHS/DVD copy of the film. Therefore, many of the versions of this film available on the market are either severely (and usually badly) edited and/or of extremely poor quality, having been duped from second- or third-generation (or more) copies of the film.
In the 1960's, producer Alex Gordon approached Boris Karloff about remaking "The Ghoul," figuring that by then Karloff was in his 70's and could play the part without the heavy age makeup he'd used in 1933. But the projected remake fell through.