Excellent LOTR Continuity Theory.

[Manwë Súlimo]

Ugh.

Look, for starters, Eagles aren't taxi cabs or tame horses that you can ride whenever. Eagles are sentient and proud, descendents of spirit-like beings not unlike Gandalf himself. Second, Eagles aren't the good guys. They aren't the bad guys either, but they don't go out of their way to help people. In some ways they're wild like normal eagles (eating small livestock of the woodsmen who live in Mirkwood, for instance), not terribly concerned with the conflict of good and evil. In the instances where people DO ride them, it's for pragmatic reasons. Gandalf got to do it because he once saved their Lord from a death by a poison arrow (from one of the woodsmen, if I recall correctly, who justifiably shot at him for stealing his sheep). They only help Bilbo and the Dwarves in "The Hobbit" because they want to troll* the Orcs and cheat them of their sport.

And even if Frodo hitched a ride on Gwaihir the Winglord, he wouldn't stand a chance against nine Nazgul on flying steeds, toxic fumes of Mount Doom, countless arrows fired from below by Orcs, and the ever-wakeful eye of Sauron whose bare will alone could hinder his flight. No. The Quest was only successful due to common bravery, secrecy, sacrifice, and (ultimately) a tripped foot of a shriveled old murderous Hobbit named Smeagol.

* - No pun intended.

[KingsGambit]

I don't really even see how this is considered a plot hole to begin with. The eagles flew over to Mount Doom when Sauron was very occupied.

[Cerebrum123]

I got this linked to me on facebook. Here's the original. http://m.tickld.com/x/this-guy-just-...ngs-mind-blown