At least two additional monsters were at one point intended to be playable: Anguirus (named "Angilas" in-game) and Rodan. Both have sprites and incomplete programming in the game's code, although "Angilas's" were removed in the international version to make room for title screen assets.

The game features two cheat codes that reference previous Godzilla films. By entering the code "DESTR0Y ALL M0NSTERS," the player is taken to the Earth stage with all the enemy monsters, referencing the movie of the same name. By entering "M0NSTER 0," the player is taken to the Earth stage with only Ghidorah as an enemy monster, a nod to his name in Invasion of Astro-Monster (known as Godzilla vs. Monster Zero in America).