If Nagato had the rinnegan the whole time, why didn't he revive Madara sooner? Like WAY sooner.
When Madara had the rinnegan, why not revive his brother?
When it was reviled that sage mode can hurt the powers of 6sop, then why minato didn't use that power to help out earlier?
There is a lot more but I can't think of it atm
1. As far as Nagato was concerned Madara was alive and well, [Obito], Obito went as far as to tell him the Infinite Tsukuyomi plan that ''he'' came up with
2. Madara as Obito, became warped enough to believe regardless of his brother coming back, the world is still at fault and it was up to him to end what he views as an ''Imperfect Word''
3. After Naruto landed the first blow, Obito went extremely defensive and Tobirama mentioned that a sneak attack like that would not work again. It wasn't until after a few chapters that Kurama mentioned to Naruto that he may be able to merge the sage chakra with his own to maintain the power of the Kyuubi as well as be able to land blows with Sage chakra. Minato was handicapped in losing an arm, and he and tobirama were supporting the two [Sasuke and Naruto] who were using a mix of Unique powers [EMS and Curse Seal and Kyuubi and Sage chakra]. The real question is Minato unable to mix the kyuubi chakra with sage chakra? would answer all the questions.