Rails? We ain't got no rails! We don't need no rails!

I believe you mean, "Where we're going, we don't need rails." Which might be an actual line at the end of BttF3, it's been so long since I watched it.

Take the rails, leave the exposition.

"Wait, isn't Nat delirious and hallucinating?"
"That's why she's the perfect person to run things!"

so anybody got a storytime about when the role of GMing was left to an invisible unicorn?

Well, I kinda wish the Friendship is Magic season 2 premiere ended with Pinky staying evil the longest and Discord grants her a unicorn horn that specializes in turning invisible. So to complete the team and take on Discord, Twilight would have to actually capture the invisible pink unicorn.

Tabletop stories, no.

Discord giveth, and Discord taketh away.

I don't have that. but once the GM got pissed (well, not really pissed, more like pleasantly pissed) at our blatant attempts to fool him and said "Of course, i saw through your plan. Even a dog would have seen that coming! i'll prove it. you know what, the dog is the GM, now."
And soo for 3 turns, he called to the dog before taking a decision and had the NPC act depending on how the dog reacted. he also had the dog do his dice roll (and before your ask: put the dice on the dog's head, he will shake it, they will fall).
In game events remained surprisingly coherent despite such a random decision-making system.

...if Spaghetti is invisible, how does Nat know she's pink?

Who are we to argue that Spaghetti isn't pink?

Because if she can't be seen, how can she be pink?

The real question is "how do she know that her name is spaghetti?"

Spaghetti said so, and she'd know, right?

It's like asking how Elwood knew Harvey was 6 feet 3 1/2 inches tall

Except height isn't something dependent upon your ability to see it.

you know, with her penchant for creating detailled backstory and setting, and her narration, Nat could make a good GM for a story-driven group.
She has some potential for that.

That's if, the group could stand a novel's worth of exposition every session.

I think someone called Beetlejuice to increase the chaos, as it was not enough...