My theory is Mikey went into a portal when Dimension X was less aligned with Earth then when the Turtles went in, so the time difference for Mikey was different. Less time passed in the real world because Dimension X was more aligned with Earth. That's just my theory.
Ahh, I remember when I tried to come up with fanonical scientific hypotheses to help explain the events of this show. :) One of my theories was that the events of the first two and a half seasons happened in only several months, to account for the turtles still being 15 in season 3. But then the end of season 3 had to ruin that by confirming that 1 season = 1 year in-universe.
Sometimes a plot hole is just a plot hole. Though it might have been nice if the show at least tried to explain the discrepancy.
There's also the thought that every portal the Kraang closes upon using creates ripple effects through-out the space time continuum, making it so the characters interface time differently.
If that were the case, it would mean the Kraang themselves wouldn't be able to rely on their own portals to synchronize their work, such as during The Invasion, Part 1.
Also, noticed another plot hole in Beyond The Known Universe: Honeycutt said they couldn't go back in time six months a second time if they were to fail, because the black hole sucks time. But that's not how it works with black holes. All gravity wells cause time to slow down by a certain degree, including the Earth's own gravity well. And at a black hole's event horizon, which is the strongest gravity well, time stops completely. But implying a black hole could suck time in the past before its creation, and furthermore make time travel impossible even light years away from it, is a huge plot hole.
Also, noticed another plot hole in Beyond The Known Universe: Honeycutt said they couldn't go back in time six months a second time if they were to fail, because the black hole sucks time. But that's not how it works with black holes. All gravity wells cause time to slow down by a certain degree, including the Earth's own gravity well. And at a black hole's event horizon, which is the strongest gravity well, time stops completely. But implying a black hole cou afld suck time in the past before its creation, and furthermore make time travel impossible even light years away from it, is a huge plot hole.
1. Whose to say after eons of messing with time-space that they haven't created algorithms in order to compensate? Of course it is ALSO possible that they didn't find ways to deal, as the Kraang hivemind is... a bit lax.
2. Black holes probably work different in their universe, infinite multiverse baby!
We should also bring up how it wasn't made through natural means, maybe that added a factor to the crazy time stuff.
I have decided to ignore the time flow between Earth and Dimension X. Its just to confusing and makes no sense. The writers ignored it in one episode so I shall too...only was everyone really confused about how long Mikey was there? He said "I've been here for months..or hours, I don't have a watch," meaning he's just being typical Mikey and apparently doesn't know how long a month is. Either way, I'm still ignoring it haha