At one point when Kenji Sawada is fending off the nuclear plant workers, the sound effects are taken from the video game Space Invaders (1978) which was enjoying massive success in Japan at the time of the movie's release. The movie begins and ends with exactly the same sound: a ticking clock, and then an explosion.
The song Makoto is humming while preparing to open up the plutonium capsule is the theme song for Astro Boy: The Brave in space (1964).
At the beginning of the movie when Kido turns on the tv, the show that is playing is Ultraman Leo (1974).