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.
Nightmare Fuel: The description of nuclear war. Granted, it was Sagan's informing people of this horror that helped to save the world from this fate, but...
The sequence in "Heaven and Hell" depicting the environmental destruction of the Earth.
The "alien abduction" sequence at the beginning of "Encyclopaedia Galactica". Yes, it's debunked immediately afterwards, but only after scaring you quite badly!
Some Anvils Need to Be Dropped: And how! Sagan spares no expense in stressing the importance of promoting science and knowledge of the world, as well as raising awareness of the dangers of irrationality.