It’s peculiar, upon re-watching the episode for the umpteenth time, I realized that Jefferson’s hat basically correlates to the Doctor’s TARDIS; Time and Relative Dimensions in Space ( referencing Doctor Who, sorry if you don’t watch ).
I only draw this parallel because while I do believe that each door leads to another world, I hadn’t considered different planes of existence. To clarify, I think a different world thereby means you’re in a different dimension but there are entities & worlds that can exist in a void. This kind of runs parallel to a pop culture theory of human instrumentality, whereby the collective consciousness of all humans in the universe, are melded into a single entity, a hive mentality. In effect, the hat might be it’s own world, acting as a sort of limbo for anyone who enters.
I don’t know, I just think they truly have boundless possibilities in regards to these doors.
Plus I think it would be interesting if they do another Alice in Wonderland episode if they choose to further explore the idea of ‘dream worlds’. But I’ve rambled long enough & probably derailed this whole topic.
My apologies if this is inconsequential, carry on.