Despite the film being made for children as part of Toho's Champion Festival, it's one of the few Godzilla movies with nudity as there is a scene in which Katsura's breasts are exposed (albeit a prosthetic). Actress Tomoko Ai recalled that she actually dozed off during the filming of the scene mentioning, "Everyone told me not to move, I got nice and cozy, so I just fell asleep. This scene was cut in the US, both for the heavily edited theatrical version and the extended TV version.
While filming the scene where a revived Godzilla vengefully charges toward Mechagodzilla (who unleashes his entire arsenal of weapons on him), the back of the Godzilla suit accidentally caught fire in one shot. This shot nonetheless remained in the final film.
Titanosaurus was the last monster introduced in the original series of Godzilla films, representing a sort of return to the more naturalistic monsters common on the 50s and 60s. Effects director Teruyoshi Nakano choose to give the monster a bright red color not only to distinguished it from the darker colored Godzilla, but he had also read an scientific article that theorized dinosaurs may have been brightly colored to absorb less heat in warmer climates. But since Titanosaurus never got popular with fans this remains its only movie appearance.
This was Akihiko Hirata's final appearance in the series. He was scheduled to appear in first film in the Versus/Heisei series but died from cancer just before production began.
This, the 15th Godzilla film, is usually cited as the last entry in the original Showa series, in part because of the oil shock (energy crisis) of the 1970s, which had severely affected both film and TV productions. After almost a decade of failed film proposals by Tôhô to revive the character, the series was continued in 1984. Gojira (1984), is technically the last actual Showa film, (being made during the Showa period which ended in 1989). However, since it lead to a new series of films, originally called the Versus Series, it was grouped into what later referred to as the Heisei Series.