I think that the Kyubi in Minato has also a consciousness, at least it would explain that Oro's arm, which didn't have consciousness, were automatically freed (since only death bounded it), while the Kyubi part didn't. The other possibility is that perhaps Minato came to terms with Kyubi within the Mask, so that when they are released, the Kyubi won't need to wait (for an undetermined amount of time) for a revival and would prefer to come out together with Minato.
Minato's and Naruto's seals is different from the one that Mito and Kushina had. That's quite strange considering that those seals were made with Uzumaki knowledge, yet Minato's proved to be better, or is it that Minato is the only person (beside So6p) skilled enough to pull off such a complex seals (this would make some sense).
Still, when Minato first sealed Kyubi, he said that it's chakra was heavy and it basically paralyzed him, so how does he now jump around like he was a feather ? It seemed as they didn't know what was happening within the Mask at all. What's more, a Jinchurki can't use the Dead Demon Seal, so come after using, Minato now is a Jinchurki ? Seriously, this seems plot-holed.
Sasuke, well I did see that coming, though I didn't think that Kishi would make it so dumb...
Sakura... hahahah, now that's a good joke, power, buhahaha, whatever power she has, she won't do much. If Naruto in SM couldn't take Pain on, then I doubt that whatever Sakura pulls out can even affect Jyubi. Unless she pucked her chakra to her fist on atomic level, then I guess when that fist is released the earth might really be shattered.