Dung beetle looks like what would happen if someone skinned Kyubey and turned him into a purse. This Troperdid realize this while looking in his fridge.
Dung Beetle tells Jun at one point that one of the other prospective pilots from his own Earth attacked Kokopelli with a knife and gave him a scar. Kokopelli gave the other pilot a scar in return. At the very end, when we finally see Dung Beetle's real body, he has a large scar on his face...
Ushiro's blood type is A, and Kana's is type O. If you know anything about blood type inheritance, you know that this is not possible if they're really blood siblings.
It is possible if the parents have both an A-blood allele and an O-blood allele.
Fridge Brilliance: Now, you might think that Hatagai gets away scot-free, right? Wrong. Remember how whenever someone wins a robot fight, some universe blows up? Yeah, so instead of one Hatagai getting what he deserves, we have multiple Hatagais paying for their crimes.
Furthermore, based on some subtle evidence it becomes quite clear that this is not our Earth, making the title something like an inverted form of Exactly What It Says on the Tin.
More Fridge Horror: There's no way the earth is the only inhabited planet in all those alternate universes. If that's true, than the death total probably several trillion more than it is now. And not only that- Imagine you live on one of those planets. You have no idea what's going on, and no way to realize that pretty soon, someone's gonna fuck up, and your world will be destroyed along with theirs.
It should also be pointed out that in the manga, after Ushiro and Koyemshi happen to see their world's version of the dead Youko, they have a discussion. Koyemshi says that seeing her in another world was a complete anomaly, and they shouldn't expect it for anyone else. There might not be another Hatagai out there, much less one who is a rapist and blackmailer.
In Kodama's fight, the characters notice that, in stark contrast to Kodama, the enemy robot was trying not to damage the city. This is most likely because the enemy didn't know that this was an "away game" for them, like the main characters during Nakama's battle, and wondered if Kodama's reckless destruction was proof that he wasn't in his home universe.
As if Chizu getting pregnant with Hatagai's son (as a result of rape in the manga) and the child dying along with her was not bad enough, there's also the implication that her child, as a contracted pilot, could have been chosen to fight despite lacking the ability, thus resulting in Zearth's defeat and the world's destruction