Hobgoblins/Fridge

Fridge Logic

 * Why didn't they just blow up the hobgoblins in the first place, rather than keep them locked up for decades?
 * McCreedy likely couldn't have gotten another job due to people blaming him for being crazy for telling the story of the hobgoblins. He waited until he was fired, void of any responsibility, and in a position where he could get back at the studio's owner for firing him (after all, the insurance company won't be happy to learn no one was on duty).
 * Or as Phelous points out, McCreedy could just lock the vault to begin with.