This is pretty great.
It's just an incredible tribute, it really is. (And even though I'm not a big comic reader, I recognized basically everything they put in without help from the annotations they put up for it. Pretty sure I recognized a thing or two they left out, for that matter.)
It's kind of funny how the Mechanical Monsters, the robots from the same-titled Fleischer Studios Superman short, have become a symbol of those cartoons. I mean, there's a good reason-they're visually distinctive and easily packaged because they're entities rather than locations (they're also from one of the less offensive of the old cartoons overall, although check out this one-admittedly, it has some offensive elements, but it's also progressive because its mad scientist is a Native American [of course there's a mad scientist, it's a Fleischer short]).
And yes, I'm disproportionately concerned with the Fleischer shorts. I watched them a lot when I was a kid.