This film marks the anime debut for 'Katsuhiro Otomo', who provided the character designs, some of the key animation, as well as illustrations (movie posters, scene in the film where Genma attacks Tokyo).
Genma literally means "phantom demon" in kanji.
The sound of Genma dying is actually the cry of an elephant played at half-speed.
The adult movie that Jo tries (and fails) to get into stars Jennifer Welles, although it's not clear which film it is.