I'm replaying it right now (the important part at least)
I'm making sure I didn't miss anything
Edit 1: In the scene mentioned in the screenshots, Hinata calls this situation the "Multilayered World Hypothesis" and compares it to the "Tri-sahasra-mahasahasra-dhatu" (
http://www.chinabuddhismencyclopedia.com/en/index.php/Tri-sahasra-mahasahasra-dhatu )
Edit 2:
"{HE}: For starters, what we experienced in the lower strata worlds were reiterations of what happened in our world. Like a mirror image. The reverse is true; the events of the lower strata worlds have also affected the upper strata worlds. Like how after a lower Mutsuki woke up, the upper Mutsuki woke up as well."
Ishtar: Another possibility is that the uppermost strata worlds is a supperposition of ambiguous states, and decisions set in the lower strata worlds propagate upward and get set there too..
{HE}: In any case, it's still uncertain as to why this sort of multilayer was born.
Ishtar: Furthermore, each and every layer is an exact replica of the same world, like they've been copied"
(LEM later says Ishtar she is wrong, and that each layer /seems/ the same but "the truth is not always as it seems with the naked eyes". There are unnoticeable differences. The layers are all slightly different, though still very close)
A bit later:
"Hinata: through quantum calculation, {Marduk} sees countless dreams in parrallel.
Which explains the multilayer structure.
"Mayumi: And at the time of the first eclipse, dreams and cyberspace overlapped."
To be short: Marduk have infinitely many dreams. At the eclipse, dreams and cyberspace overlapped, but later in the story cyberspace and reality overlapped too. Kinda making the infinite worlds "real".
Even later:
"Ea: Can you tell me the difference between dreams and reality? [...] Are you sure you are not misunderstanding where you are, where "here" is? If you do not understand, then there is no beginning, nor an end, is there? To run away from reality before your eyes and seek an imaginary reality. Is that not what the exact thing you are attempting? There was never a multilayered world structure to begin with. You have only the real world, diving, deeper and deeper into yourself. Like gazing into overlapping mirrors. [...] There is no possible way for 'infinity' to exist. If there is no end, how can you be standing still 'here'?"
LEM: Besides, in this multilayer world, you can't find the exact path without recursion
Hinata: Why not?
LEM: Because all of them are real.
Later it talks again of the multilayer structure as infinitely many very similar realities, but "superposed" like a quantum bit.
Basically, there is one "real" world with infinitely many superposed states, its "layers". Like in quantum mechanics
And that's all for route E. (previous routes didn't mention at all the infinite worlds) If you want to see the full context of these quotes you can use the youtube walkthrough. Its route E, near the end.
There's also the "prime" routes A' / B' / C' / D' / E'. I'll check them too and post here if I find something relevant.