Both the New World Pictures and Toho versions serve as direct sequels to the original 1954 "Godzilla", with "Godzilla 1985" also serving as a sequel to "Godzilla, King of the Monsters!". The same adaptation techniques used to produce "Godzilla, King of the Monsters!" were implemented with "Godzilla 1985", with the original Japanese footage being dubbed and edited together with the American footage. The film retains the original musical score by Reijiro Koroku, while also integrating portions of the score for the 1985 Canadian film "Def-Con 4", composed by Christopher Young.