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: Late in the book, Katie has a dream of living all alone in a decrepit old house which sits isolated from a burning city with giant walking skeletons.
Also from that scene, when Katie turns Alex over in bed, she's greeted by what looks like Alex's corpse (with glassy unseeing eyes and a dead expression), which ends up basically being an inanimate statue that cracks apart at her touch.