I remember watching this show, and particularly this closing scene, on tv sometime between 1972 and 1974 (i.e. ages 8-10). It caused Giant Robot! to become permanently embedded in my vocabulary.
I also remember thinking (not precisely in these words) that if the proportion of explosion-caused-by-destroying-the-monster to explosion-caused-by destroying-the-monsters-fingernail is no greater than the proportion of the monster to its fingernail, the bigger explosion wouldnt be enough to destroy the Earth.
In other news, the following promos look generally promising:
I was always amazed that the unicorn organization gave Johnny Sokko the code number U-7 right off the bat. If your number in any way signifies your rank, then there are only two possibilities: either there were only six other members of Unicorn when he enlisted (which, given the small number of extras running around the Unicorn base at any time, is entirely possible) or Johnny started his career a very high-ranking officer (I suppose having a giant robot at your command would open a few doors, career-wise).