These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
What Do You Mean, It's for Kids?: Some of the later stories rivaled the Mirage book in terms of grittiness, even though this was the kid-friendly TMNT book. This unfortunately led to problems with the editorial staff at Archie Comics.
To elaborate: The Mutanimals were brutally shot to death on-panel. Despite time-travel being involved, the team stayed dead. When it was revealed the demon Null was behind it, he disguised himself as one of Candy's deceased friends just to torment her with an image◊ of the Mutanimals burning alive in hell.
Another storyline had future versions of the TMNT travel to the past, where they met up with Adolf Hitler. They tricked him into committing suicide◊.