Trivia / Gamera vs. Zigra

• Creator Killer: Daiei was facing serious financial troubles at the time, and Gamera vs. Zigra was the last film they released before the company declared bankruptcy and dissolved three months later, and its assets were acquired by Tokuma Shoten.
• Franchise Killer: Declining ticket sales led to Daiei declaring bankruptcy only a few months after this film released, causing a sequel (Working Title Gamera vs. the Two-Headed Monster W) to be scrapped before production started. It would take nine years for the franchise to see the light of day again with Gamera: Super Monster, and even then only as a No Budget Clip Show that put the series on ice for another fifteen years.
• Dueling Movies: With Godzilla vs. Hedorah as the two films came out just one week apart, and both have very similar themes of being anti-pollution and the effects it has on ocean life (in both cases being Ripped from the Headlines, as there were numerous large-scale environmental disasters in Japan around the time due to its rapid post-war industrialization).
• No Export for You: Unlike the earlier films, Gamera vs. Zigra did not see an overseas release until 1987.