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.
YMMV: Z for Zachariah
Nightmare Fuel: Imagine being in Ann's position. Living on your own with no one around, with the possibility that you may be all alone in the world now. She even admits that she refused to let herself think about when the food runs out.
What her family found on their first trip outside the valley, as well as Ann's description of what she sees when she climbs to the valley's edge: she calls it "the deadness" because everything, even the plants and trees, are dead and brown. Made extra horrifying by the fact that her family hadn't intended to be gone very long on their second trip — it's implied that things were so bad that a short excursion was enough to kill them all before they could get home.