No Export for You: There was a very long pause of Godzilla movies not being released over to the U.S. and it started with this one.
Explanation: There was a huge controversy over the footage of Godzillasaurus killing American G.I.s during the WWII sequence, along with the fact that the main villains were Westerners. This, coupled with the strained economic tensions between the U.S. and Japan at the time, resulted in the aforementioned long pause in U.S. distribution. Word of God explained the film was never meant to be anti-American.
A direct sequel was planned after this entry did well at the box office. This time with a King Ghidorah whose origin was more in tone with his Showa counterpart, a space monster.
Rather than under the sea in 2204, Tomoyuki Tanaka wanted King Ghidorah to be discovered on Venus (which he was associated with in the film 'Ghidorah, the Three-Headed Monster'). Writer/director Kazuki Omori was somehow able to override Tanaka's objections because he didn't want to make a movie about "silly space monsters." The Japanese novelization for the film ran with Tanaka's idea, in that the Futurians discovered the body of King Ghidorah partly buried on the surface of Venus and used his cellular materials to create the Dorats.
Godzilla's original form was going to be a Tyrannosaurus rex, until special effects designer Shinji Nishikawa opted for a fictional dinosaur species instead.
You Look Familiar: Yoshio Tsuchiya returns to the series in his final role, as Yasuaki Shindo.