Warning, spoilers follow. Stop reading if you haven't seen the series through.
If you like the anime Fushigi Yuugi, you know that the final episode kicks ass. There's a cool extended instrumental remix of Tokimeki na Doukasen and in the epilogue, as you would expect, Tamahome returns to Miaka's world through the Power of Love.
Anyway, you know that guy who was Miaka's brother's friend? All you know about him is that Miaka's brother owed him money which he wanted a lot, and that he helps out the good guys a few times for no apparent reason. Why would he do this? It doesn't make sense.
Anyway, in the epilogue, Miaka's brother says that a special person has come to visit him from far away. Obviously, that's Tamahome. So then in the very next scene, there's the brother's friend taking up like the entire screen. So instantly I'm like, yes! stroke of genius! that guy was Tamahome all along, a parallel Tamahome because of some time travel deal, who couldn't admit until now who he was for fear of changing the course of time. That's why he likes cash, and why he's so enthusiastic about helping Miaka. Why didn't I realize it before?
But in the very next scene, rather than removing his sunglasses he's always wearing to reveal Tamahome's face, you see that Tamahome is just waiting behind him, and the friend is just a stupid secondary character after all. Argh! I feel like going to the script writers and rapping them on the head. It would have been an absolutely beautiful plot twist. 26 episodes that Tamahome was walking among us and we didn't even realize it. But, they didn't think of it. Sad.
This is probably related to the manga, which continues after the TV series ends. Still, it would seem worthwhile to sacrifice consistency in this case for a far more kickass ending.