As I was rewatching the first Teenage Mutant Ninja Turtles an odd thought occurred to me: the least plausible part of the movie might not be the titular heroes, it might be their foes, the Foot Clan. Now I know what you're saying: everyone in The Foot Clan is a human, so they are automatically more realistic than the Turtles, who are grossly misshapen monsters that could never actually exist. You'll notice however, that I didn't say realistic, I said plausible. Of course ninjas were real and mutant turtles are not - but if we assume that we were suddenly in a world where both existed, then it's easier to imagine those real mutant turtles acting like the movie mutant turtles than it is to imagine those real ninjas acting like the movie ninjas.
Let's look at the turtles first. Ok, sure, the idea of magic ooze making a turtle grow to be six feet tall and bipedal is insane. Naturally, the idea of any sort of turtle ever having enough flexibility to do ninja moves is crazy. The movie has no explanation for how any part of their anatomy works, nor does it explain how they stay in such great shape despite eating an all pizza diet. Fine: their backstory doesn't work.
But what about their in-the-moment story? That starts to check out immediately: of course they live in a sewer, because what real estate agent would show them an apartment? They talk exclusively in unnatural sounding soundbites - but they were homeschooled, of course they don't really know what normal speech is like. It's weird that they are friends with a giant rat, but then again, beggars can't be choosers. If I only had three friends and somehow I found myself in conversation with a rat the size of R2-D2 I'd think twice before I looked down on him.
I'll give you that it makes no sense that once Raphael throws on a hat and a trenchcoat he can buy a movie ticket without the ticket seller realizing that they are talking to a "man" with an oblong green face. I know that the movie's set in New York City and New Yorkers are used to crazy people - but come on, no one gets used to that. However, that's still only minus one on the plausibility scale.
Now let's consider the Foot Clan. The Foot are an ancient order of ninjas which has relocated to New York City. So far so good - NYC is of America's hub for immigrants, after all. Their main recruitment strategy for new ninjas seems to be suckering teenage delinquents in with promises free cigarettes and endless card games, then pulling a bait and switch and actually training them to be a crack team of invisible thieves. This makes a lot of sense, because the number one group that takes well to discipline is angry teenage boys. Also, if you want to find a population that's interested in blending in, that's a good demographic to recruit because none of them enjoy making noise, putting on a show or puffing themselves up.
Furthermore, the Foot don't do any background checks on their recruits, meaning that a lot of the kids they've suckered in have rich parents who aren't going to be down with their kid joining a gang of ninja-thieves. Somehow, a group that's obsessed with being invisible is more indiscriminate about who they let in than your average cult? If those pesky Turtles hadn't intervened, I'm sure the Foot Clan would have stayed undercover forever.
The Foot's leader is a guy named Shredder who wears a red suit and a gigantic metal mask - because if your goal is stealth, nothing works better than bright colors and reflective surfaces. Underneath his mask Shredder is Japanese, which you can tell because "Shredder" is the most Japanese name possible. His goal is to become the new crime boss of the city, and to that end he's using the best parts of the Mafia's playbook - meaning that he wants his men to look totally inconspicuous, he wants them to concentrate on low risk / high reward crimes, and he has a bunch of semi-legit businesses he can funnel his cash through. Just kidding, his men wear head to toe black skinsuits with tea strainers over their eyes, they mostly steal wallets on the street during broad daylight, and their main headquarters appears to be in an abandoned warehouse that might be in a sewer.
Seriously: The Foot's modus operandi is insane. Their organizational structure makes less sense than your average internet conspiracy theory, which is saying something, because your average internet conspiracy theory contends that lizard people secretly run the world. (This movie just asks you to believe in lizard people, not in their total world domination.)
Of course, neither the Turtles nor the Foot is ultimately that credible. But it doesn't really matter - the film isn't trying for verisimilitude. It's intentionally goofy, all broad jokes and cartoony violence. Its lack of pretense might be its saving grace, actually - it holds up surprisingly well, and that's mostly due to the way it leans into its inherent ridiculousness with a smile on its face. Sure, the jokes are corny, the plot is beyond featherweight, and the martial arts action is slightly (coughcough) below your average Jackie Chan film - but it's still charming enough that I would call it fun, even if I wouldn't call it good. Maybe it's a bit implausible that these movie turtles would be so eager to please when most real turtles don't give a shit about entertainment, but you know what? I'm not going to look a gift turtle in the mouth. (But that's mostly because their mouths are easily the weirdest part of their weird bodies.)