Let's start off with the Smog Monster himself, Hedorah. Godzilla has appeared in nearly 30 feature films, and for my money, Hedorah is by far one of his toughest opponents. Sure, Hedorah can shoot heat lazers out of his eyes and spit toxic loogies -- he can even shift shapes (an ability later seen in such foes as Orga and Destoroyah). That's all well and good, but Hedorah is also an entity of living sludge. This not only renders Godzilla's bread-and-butter -- his atomic breath -- fairly useless, it allows Hedorah to regenerate himself simply by consuming more pollution. As you see in a bit, Godzilla needs to dig deep into his bag of tricks to get the best of Hedorah.
But really, this film belongs to the hippies. Watching this critically for the first time, I was struck by how radical the movie was. The film itself was released just a couple years after Woodstock, and it really shows. What is mankind's solution to taking on the scourge of pollution? Hold a rock concert at the top of Mt. Fuji, of course! This is, to date, the only Godzilla film to feature an acid rock music video (complete with trippy fish-headed dancers):
But hippie power doesn't stop there. No sir! As if the movie's message wasn't heavy-handed enough, we have a villain that practically fellates those industrial smoke stacks, just as those in power today fellate the oil companies. We then see the unrestricted corporate monstrosity fly around the country, gassing and killing hundreds of people (of all the Godzilla films, this one may have the highest body count). Hell, Godzilla performs abortions on the little Hedorah egg-spore-thingies. Someone should notify the Catholic League.
Looking at the film critically, it's all pretty dark stuff. Well, not all dark. There is one other thing this movie is well-known for...