In the first film, the Foot Clan's ambush of the Turtles and April at 2nd Time Around is escalated when one of the Foot mooks swings a Bisento axe and cuts through a power line, ELECTROCUTING HIMSELF, as well as starting a fire. Furthermore, the gang (including a gravely injured Raphael,) only makes it out alive due to the intervention of Casey Jones, and pretty much at the last second. We see April and Danny Pennington respectively, both distraught, watching her apartment go up in flames. What we don't see is how (or more appropriately, IF) the dozen or so Foot ninja that were knocked out during the melee ever escaped. You may write this off as "They're henchmen, so who cares?" Well, remember that the bulk of the Foot's recruitment (we never find out how many emigrated with Shredder from Japan) was aimed at TEENAGERS, some appearing as young as 13.
Slightly mitigated in that the Foot seem to recruit on a "milk before meat" approach in the first film: they lure in young teenagers with promises of cigars, skateboards, and other fun, and as the children get older they are taught martial arts and eventually indoctrinated into becoming Foot Soldiers, meaning that the ninjas attacking the Turtles are likely to be at least 18.
The characters of Tokka and Rahzar from Teenage Mutant Ninja Turtles II: The Secret Of The Ooze fall under this. Remember the fights they had with the heroes? Remember how they are essentially defeated by being tricked/force-fed into eating anti-mutagen changing them back to normal? Well, now take those battles into consideration when you remember that they're babies.
It's even worse when you remember that Shredder pretty much sent them out on a destructive rampage by tricking them into thinking that's what "playing" means. In other words, Shredder pretty much brainwashed two innocent children (albeit said children are a mutated wolf and snapping turtle) into endangering themselves and others for "fun".
They're not actually babies, Professor Perry sabotaged the mutagen that created them to make them less intelligent (and therefore less of a threat) and the final shot of them returned to normal shows that both Tokka and Rahzar were full grown.
Which provides another type of Fridge Horror as there is now a full-grown WOLF in the middle of a crowded nightclub of people!!
But they did act like children... which means that Professor Perry probably made Tokka and Rahzar mentally handicapped!
At the end they show the two un-mutated, and while its hard to tell Tokka's age (But probably older given how long it takes most turtles and tortoises to grow to that size) Rahzar is definitely immature (if not an actual puppy).
More squicky than truly horrific, but in the first movie, April has to spend a lot of time walking ankle deep through drainage water while wearing a short skirt and high heels. Make's her animated counterpart's yellow jumpsuit seem both practical and hygienic.
When the Turtles are returning to the lair from the farm she's actually carrying her shoes, which is somehow both better and worse at the same time.
Shredder's fighting technique used during the battle with the turtles at the end of the first movie. If you watch his movements you see he is being very conservative. A few quick blows, then stepping back. Never exposing himself by going for a Killing Blow and letting the turtles come to him instead of running at them. As he is fighting against four other people probably not even half his age if he were to get winded or badly hurt he could very easily be overwhelmed.
There's also a possible hint of I Let You Win as you realize that the Foot possibly never meant to actually beat the Turtles, but lull them into overconfidence and lure them to the roof where the Shredder is waiting or just wear them down making them easier to fight.
When they find their home ransacked and Splinter missing. Raphael takes it harder than the others. Though this may be his classic rage breaking on the surface. If we really look into it, he blames himself because he manages to piece together how they may have found their sewer home. Judging by the look on his face he was thinking about the events prior to April meeting the turtles, from the Subway fight to escorting her home.
The Shredder threatens to our heroes by telling them that he was going to dine on turtle soup. Sure, it sounds silly, until you think about what that means. He basically said he was going to kill, cook, and eat our heroes.