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.
And then there's "Eternity," taken directly from Blue Dragon. It's sung by Ian Gillan of Deep Purple. The song's meta-info for the artist even says "jesus christ the guy from deep purple sang this." See the Blue Dragon entry for more info, but it garners the exact same reactions here—which is certainly why it was used.
Demonic Spiders: Dread Refs appear as a miniboss in the first dungeon, and then as normal enemies later on. They can summon more Dread Refs, and also inflict foul on you, making you miss a turn. They also have a relatively strong, multi-hit attack.
Fan Dumb: Parodied by the Pumps, who spew long, pretentious rants at you about the superiority of Japanese "vidcons" whenever you're trying to save your game.
Good Bad Bugs: While enemies don't typically respawn, it's possible to make them respawn by saving, quitting to the title screen, then loading the save file. Using this it's possible to grind for more money and experience.