- What She Wants revealed that all of the teens in Sidney's ghost Casper High will be there forever. Sidney only gets out thanks to Desiree hearing him while on a wish-granting spree, allowing him to graduate. Now think of other students who are probably miserable like Sidney was and can't graduate...
- Word of God likes to wonder if they are real ghost students or rather just extensions of Poindexter, much like the band Ember had in her first appearance.
- Vlad's Mind-Control Device: Some little tiny ring shaped device can be stuck behind your ear, where no one will see it. It will completely override your thoughts and turn you into a puppet. Then a ghost like Vlad can turn intangible, sneak up behind you, and put it there.
- Nocturnes's plan for Danny and Sam in Hearts and Minds. Trapping them in a dream where they had no memory of each other was bad enough, but he actually attempted to steal all their dream energy and leave them trapped in a Deep Sleep.
- Danny's alternate ghost mode. Not only does it cause Danny to slowly become feral, but after using it for too long, the ecto energy will build up to the point where his body will burn out.
- After capturing Danielle when she was protecting a deaged Danny and Sam, the Guys in White were planning to experiment on her. And she is (technically) ten. And they wanted to do the same with a deaged Danny and Sam, who were five.
Nightmare Fuel / Facing the Future Series