Also known as Destroy all Planets, Gamera vs Viras shows that as early as the 4th movie of the original 8 film Gamera series, they were already running out of ideas. Seemingly taking several pages from the Godzilla film Destroy all Monsters plotwise, what the budget didn't allow the producers to fill in they simply made up for with liberal use of stock footage. This amounts to quite a strange feature... but is there a silver lining to this cloud?
Source: Gamera vs Viras Movie Review action movie reviews - Decker Shado