It's not realy like the idea of 'neurons misfiring'. I think you should rather compare it with dreaming or fantasizing. It's like the brain is actually creating dream-like imagery all the time, but this imagery, this 'dreaming' is normally being 'guided' by sensory imput.

Whenever we see something, it's not realy the senses, but rather the brain, creating the image. The senses merely 'steer' the imagery in the right direction.

So when this 'guiding mechanism' is being supressed, the brain can run it's own program. It can fantasize freely, uninhibited by any kind of correction mechanism. That's the idea.

I think that in no way contradicts what you're saying. We all know from experience how rich, how detailed and how convincing dreams can be.

But when you look at the famous 'A.I. dream pictures' that have been the result of a simmilar proces as the predictive coding mechanism, then it's clear that if pattern-recognition is not being inhibited by some kind of correction mechanism, you can easily create very psychedelically looking, multidimensional images that don't seem to bear any resemblance to everyday reality as we know it.

And the content of the experience...i have no idea why that is either. But when i sleep at night, i don't dream about spiderman either. Maybe many pop-cultural elements aren't just interesting enough for the brain to dream about.