The original premise of Highlander is pretty cartoony. A bunch of immortals fight each other to get a mythical prize, which is either telepathy or phantom dragons or something? That's actually pretty straightforward for an '80s cartoon. But where you get into trouble is all the crazy head chopping. Now, to give this series credit, they didn't change the premise too much: there are plenty of deaths in this, even if they take place in a crazy, distant future with some immortals refusing to kill and a whole new MacLeod. And it still makes more sense than most of the movie sequels.
7) Tales from the Crypt
Okay, so this technically isn't based on a movie, but rather the unrated HBO series, but considering the number of c-list celebrities hacked to death in that series, it still wasn't something kids should be watching. You'd bet kids would love a bit of gory fun, but this one overcompensated and made itself way too kid-friendly, as the type of horror stories you expected ended up being just being watered-down morality tales where everything came out alright by the end. So, instead of being about ghost stories where Bobcat Goldthwait get hacked to death, we got ones where kids learned the perils of lying. We'll take a murdered Morton Downey Jr. of sugary sap any day.
6) Attack of the Killer Tomatoes
This one doesn't make sense on any level. Why adapt a film that almost no one saw in the first place, especially when the original movie is a confusing mess featuring a beautiful girl made from a tomato who transformed back whenever Beethoven's fifth was played? We've been on acid trips that made more sense than that. They sure as hell weren't trying to appeal to all the kids that saw the original Attack of the Killer Tomatoes movies...did they think 6-year-olds were really into kitsch?
5) Rambo and the Forces of Freedom
The uber-patriotic '80s were the perfect time for Rambo... or at least the U.S. soldier he became by the third Rambo film, which completely did away with the tortured vet aspects of the character from the first two films. Which explains the G.I. Joe makeover they gave him for this show, as Rambo fought the fictional terrorist organization S.A.V.A.G.E. all without actually shooting anyone. Maybe they thought kids wouldn't be as interested in watching him shoot up a small country town week after week?