SM Minato=Plothole, although debatable
Kaguya supposedly used IT before ,but humans didn't have chakra before Kaguya, which means that somehow IT affects people without chakra system, which would blow away the definition of genjutsu.
Madara being able to use Kamui even with Juubi inside
Obito not dying countless of times.
Kaguya = Possible aliens...
Theres more that I'm probably forgetting.
1. How is SM Minato a Plothole? Fukaku (The sage frog) stated that Naruto has surpassed his predecessors with a image of minato and Jariyas back comparing Naruto to them, and this is when they were speaking about his ability with sage mode. Not a plothole, and minato was practically confirmed to have SM during the pain arc...minato also clears up that he was not as efficient as using SM and thats why he didnt waste the time doing it in battle constantly.
2. I dont have a definitive answer for this one, but i dont see it as a plothole.
3. Well, there is the possibility that when madara absorbed the god tree it negated whatever restrictions he incured from the juubi, there is also the possibilty tat madara was a perfect jin and thus was able to travel between dimensions with the juubi because of there "perfect" connection, kinda like naruto and kurama when it came to natural chakra training. Still not a plot hole even if im wrong about that.
4. It was stated that he wouldnt die from the bijuu being extracted from him. When he used the jutsu to revive madara he still had the chakra and the will to live, and he finally did die...not a plot hole, even if im wrong.
5. Well if the fact that there are different dimensions, people who can turn into snakes, people who can turn into water, swords that have mouths and can communicate, talking dogs, summoning creatures from different dimensions, peolpe that look like sharks, cats, dogs, have insects in them, peolpe whos body turns into trees, there is no reason why an alien would be a plothole...
Plothole: A plot hole, or plothole is a gap or inconsistency in a storyline that creates a paradox in the story that cannot be reconciled
with any explanation.
Outside of the Kaguya thing, there are very few events in naruto that cannot be logically explained with "proof" from the manga. There is some inconsistency, but no real plotholes..