Hell can be treated as a retcon, since we were shown multiple times what hell was in Z, and that there was one hell, but in RoF, Freeza stated something about earths hell. Meaning the planets (at least ones with life at minimum) would have their own hell.
Buu's galaxy bust is supported by Goku's Universal spirit bomb, which drew power from the entire universe, which wouldn't be Universal, but at best Multi-Galaxy (or at least enough to support Kid Buu being Galaxy level). Yes, there
are only 28 planets remaining with life, plus the 8 Beerus destroyed at the start of Super (something that happens after the Spirit Bomb, so yes, it is valid), however Goku borrows power from stars and planets themselves.
Stars in the universe:
1,000,000,000,000,000,000,000,000
Let's say one star outputs 380,000,000,000,000,000,000,000,000 j/s, which is the average
output of the su
Assuming he took a small 5% of the power of each thing is a heavy lowball, as we saw it exausted the humans on earth once they gave their energy. However, I will use 5% anyways.
Meaning from every star, he took 1.9e+26 joules, or Large Continent level energy per star. Again, this is a massive low ball, as 5% of a humans energy wouldn't be enough to tire them, yet we see that doing so exhausted them. So the final result is actually much higher.
This adds up to 1.9e+50 joules for every star in the Universe. Yes, this would be only in the middle of solar system level, however there are a few more things to be considered:
1. This includes stars only.
2. Mystic Gohan, Goten, Trunks, Piccolo and Z fighters gave their power as well. Gohan is already solar system level here, easily and there are several Large Star beings giving their energy.
3. He was borrowing power from afterlife as well, as we saw King Yenma give his power. It's possible he also gathered from the Kaioshin Realm, which is technically part of U7 and has it's own suns as well.
4. The spirit bomb is truly effective against beings with even the smallest bit of evil in their hearts. Kid Buu was completley evil, no remorse whatsoever.
Not to mention small boosts of ki provide massive power boosts (which I can mae a thread on later. It was also gone over in that hangouts call)
So I don't see a problem with MSS Kid Buu.
Freeza's contradiction is out of the way, and MSS Kid Buu can be argued. I'm not sure of any other contradictions you guys may have seen in kai, but if you have any more maybe leave a list?