The final scene of the film, lasting less than one minute, is in color.
The producers decided to use the very heavy make up on Duncan 'Dean' Parkin as a way to disguise the fact that a different actor was playing Col. Manning, especially since in a dream sequence flashing back to the original film featured Glenn Langan, the star of that film.
American-International changed the title to a more dramatic-sounding "War of the Colossal Beast" and avoided mentioning in the ad campaign that it was a sequel to an earlier film.
The airplane used to transport the Colossal Man is a Douglas C-124 Globemaster cargo plane, active from 1950 to 1974 in the Air Force and reserve units.
The "beast" makeup was created by Jack Young, who had earlier designed the titular monster of "The Cyclops" (1957). Both creatures were performed by the same person - stagehand, Duncan "Dean" Parkin.