There is a second version of this movie in Japan. It is an abridged, 2-part version done for TV, around 60 minutes long. It is incomplete, however (there are plenty of spots in the film with a Japanese "Sound Only" title card placed over audio with missing picture).
Akira Ifukube's music is mostly different from the original film. This version is available as an extra feature on the DVD in both Japan (Toho Video) and the US (Media Blasters' "Tokyo Shock" label).