This film features Godzilla Earth, the largest incarnation of the character to date, which was previously seen at the end of Godzilla: Planet of the Monsters (2017). Godzilla Earth is 300 meters tall and weighs 100,000 metric tons, with the second-largest version of Godzilla, featured in Shin Godzilla (2016), standing 118.5 meters tall and weighing 92,000 metric tons.
This film features Mechagodzilla, Godzilla's mechanical doppelganger that was first introduced in Godzilla vs. Mechagodzilla (1974), and made its most recent appearance in Godzilla: Tokyo S.O.S. (2003). Mechagodzilla was originally a weapon constructed by alien invaders, but in subsequent films has typically been portrayed as a human-built weapon created to defend the human race from Godzilla and other monsters. The version of Mechagodzilla in this film combines both portrayals, with it being built by the Bilusaludo aliens but with the purpose of defending the Earth from Godzilla.
This is the second entry in a trilogy of anime Godzilla films produced by TOHO Animation and animated by Polygon Pictures, with the first entry, Godzilla: Planet of the Monsters (2017), released theatrically in Japan on November 7, 2017 and worldwide to Netflix exactly two months later. The third entry, Godzilla: The Planet Eater (2018), was released to theaters in Japan in November 2018.
This is be the first Godzilla film to be a sequel to a prior film in the franchise since Godzilla: Tokyo S.O.S. (2003), which was a direct sequel to Godzilla Against Mechagodzilla (2002). All films released since then have been set in brand-new continuities and disregard all previous entries in the franchise.
Haruo's English voice actor Chris Niosi reportedly got so upset by the ending that he actually cried while recording his lines.