From the Goofs section
Anachronisms: This movie is taking place in the year 1928 yet at the end Dr. Phibes plays "Somewhere Over The Rainbow" which was not written until ten years later.
Okay...
The automobiles, the airplane, and film projector (showing the sexy movie) all seem to be models from the 1920s, but the house interiors (including the lights around Dr. Phibes' organ) and clothing appear modern contemporary when the film was made - early 1970s "mod" style.
Utter rubbish!