Well it’s taken me 20 years but I’ve finally found something in Buffy that doesn’t make sense. At the end of the episode where we get introduced to Anyanka, Giles destroys her amulet to undo her wish. But if that works, it must surely undo ALL her wishes — why would it just be the last one reset to the moment she made that last wish come true?
And then you have the usual time travel paradoxes:
(A) all of history would be different because for hundreds of years, different people would be in different places doing different things
(B) even ignoring A, Anyanka specifically wouldn’t be in Sunnydale (since she has no powers), so wouldn’t meet Xander and the rest of the episodes wouldn’t play out as they do
(C) even ignoring A and B, Anyanka’s old boyfriend wouldn’t be a troll, so that whole storyline wouldn’t make sense.
I need my magical demon-making-wishes-come-true and creating-alternate-timelines stories to be logically accurate, dammit!