Director, Yoshimitsu Banno, came up with the idea for Godzilla vs Hedorah after seeing cities like Yokkaichi covered in smog and the ocean filled with detergent and other pollutants.
This is the first appearance for the suit actor, Kenpachiro Satsuma, in a Godzilla movie as he plays the smog monster, Hedorah. He will go on to play Godzilla in the 90's Godzilla movies.
Godzilla fights a sludge monster that grows after feeding on Earth's pollutants.
I don't know how to describe this movie. It's all over the place. Many people say that this film looked like the movie is high on drugs and they say this in reference to this one scene at a dance club where all of the people's faces changed to having fish faces. It was one of those weird moments where you have to ask yourself what the hell was going on in that scene. The best scene in the whole movie is where Godzilla flies. It was so off the wall, but it was amazing to watch as he chases the smog monster when it tries to escape.
Even though this movie was targeted towards kids, there are some scenes that are too horrific for kids to watch. In today's day and age this would be given a PG-13 rating instead of PG, but it is still rated PG to this day. There were times where I thought that I was having trouble with the DVD because there wouldn't be sound at times, but there was nothing wrong with the DVD. It was just the movie itself. They filmed some scenes without sound and it had me confused.
Even though it was made towards kids to send a message to not pollute, Godzilla vs Hedorah is no way made towards kids without some parental supervision.