when i remixed this last night, i just ran the guitars that i recorded in 2014 through a transform to slow them down from 180 bpm to 70 bpm - which is a good ways. midi is instructions, and that's not much to deal with. but, slowing down actual audio that much is going to create artifacts.
in fact, that was a part of the design of the thing - this was intentional. i want some blurriness in the guitar. it's trippy, and the thing is trippy - it's a good match, and it fits the aesthetic. i was also expecting it to come in a bit out of phase, as the part is doubled.
see, i really did play it in at 220 bpm, which is very fast. when you're playing that fast, you can be wrong by fractions of a note and not have anybody notice. but when you then slow the tape down, the distance between the notes becomes more audible - it's still the same fraction of a bar on paper, but it's been expanded to the point where you can hear it. that 32nd note botch that i didn't even notice at 220 becomes a huge problem at 70.
it's an easy enough fix; while these were live guitars at one point, now they're just samples and can be manipulated like any other.
i have a replacement for the slow mix coming that fixes some of the phasing issues, while keeping others for effect.