Example reminding viewers that bad things would have happened if the villain won.
Example mentioning that there are actual people out there who are just like the villain.
Example mentioning that there are actual people out there who are just like the heroes, which is bad because the work is propaganda for a controversial religious or political ideology.
Example pointing out that a scene from the trailer could have bad ramifications, even though said ramifications end up being addressed in the full work.
Example pondering about the possibly horrific (though offscreen) fate of a minor character in the story.
An example going off of that
An example going off the one above, but doesn't use three asterisks.
An example going off of the one above, but wasn't put under it.
Meta-example about the fact that the work wouldn't have been made if it weren't for some fortunate coincidence.
Meta-example speculating on how the events of the work could become reality.
Meta-example about the fact that somebody made this work even though it sucks.
Regular Nightmare Fuel that is extremely obvious in the work proper.
Example that explains that without any element that lowers the consequences in fiction, the consequences would be just as bad as real life.
Complainy meta-example wondering why the work even exists when there are way better works with a similar premise out there. Why would anyone want to watch this show when they could just watch that show instead?