Unexplained solutions to villains' problems
 

Has anyone else ever wondered how in the old toon, some of the major problems Shredder and Krang had were easily fixed without any explanations?

Like in Leatherhead, Terror of the Swamps, Shredder fell in the fountain of youth and turned into a baby and in the very next episode, he was back to normal and it was never explained how he was cured.

In The Making Of Metalhead, they never showed how Shredder got out of that cement.

In The Irish Jig Is Up, they never showed how Bebop and Rocksteady turned back into their normal selves from kids.

In The Wrath Of The Rat King, it was revealed that the Technodrome was stuck in a black hole but in its next episode, it was on a planet and it was never shown how it got out of the black hole.

That stuff was pretty typical for cartoons at the time. Usually at the end of an episode they'd play a running gag that wouldn't get resolved, and then the next ep would act like it never happened.

The same thing happened in "The Big Zipp attack," when one of those monsters was left behind and started duplicating again.

Its basically done for humor. I love how at the end of a Euro episode Shredder's costume is all rusted and he screams, "Oil, I need oil!"

I think a better question is why the hell did Shredder sound like chain smoker in this episode?

I think a better question is how was Shredder able to breathe while encased in a block a granite?

Maybe Shredder and Krang threanted to give them up for adoption.

Maybe they ordered Rocksteady and Bebop to get out and push.

This and the technodrome's location switching between season 3 and 4 are the only real flaws to me.

The other things you mentioned could have been easily fixed with Dimension X technology if you wish.

Maybe Dorian Harewood smoked a lot :-?

Rust Never Sleeps
 

Rust Never Sleeps. Fun ending.

I've always wondered how Shredder returned to his right age after the fountain of youth incident, though it may be possible the effects of that mutagen-laced water weren't permanent.

In "The Big Blow Out" episodes, Krang simply pulled a lever to restore the shrunken Technodrome to its original size.

The real question is, why would Krang bother to return Shredder to his normal age?

Basically, this: "Status Quo is God".

The old toon didn't care much about continuity.

In order for an episodic toon to work, these gags were necessary. It's just the nature of fiction and fantasy. Of course since they always return to the Technodrome at the end of each episode, it's easy to assume the Technodrome's resources could fix the problems between episodes. With all the foot soldiers/rock soldiers, there's plenty who can help their masters out.

Science fiction
 

The 1987 cartoon was usually a science fiction show (most plot are like 1950's and 60's science fiction movies), while the 2003 show has more fantasy elements but also science fiction elements. So I agree, it's mostly Technodrome technology from Krang's home planet that fixes it.