Granted, I'm over thinking it...

Over-think away, my friend. You've found the purpose of these boards. And I love this movie like no other. As children, my brother and I watched it every year whenever it aired; first, evenings and then, later, on Saturday afternoons...carried away by the story and rapt by Harryhausen's effects. For years, Herbert's launching himself upon the 'phororhacos' (giant chick) defined a young man's courage to me, especially with the mark of "coward" upon him. It moves me, still...the rise of Herbert's mettle. And he and Elena lounging on the beach...she pouring warm sand idly onto his shoulder and betrothing herself while he just smiles his heaven, eyes closed...this stamped, for years, my seal of young love.

On your observation, you are wholly correct, phindar. Nature offers no free lunch. A chicken the size of a giraffe would require both commensurate resources and significant safeguards, lest we end up "on the inside carving our way out." But here's my question: How do they signal Nemo? After Captain Harding and his team insert the weather balloon bladder into the sunken pirate ship, they stand upon the raft, task completed, at least a quarter mile or so offshore. Harding tells Neb to "signal Nemo or none of us will get out of here." In short order we see Nemo on the deck of the Nautilus looking up, attentively, then throwing the pump switch. Without a cellphone and out of both visual and auditory range, how did Neb signal Nemo?

thats because the giant animals were made up for the movie. nemo wasnt solving worlds hunger in the book.

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If you want horror - tune in the news channel.

you're right a large anything would be hard to handle and very hard to transport.not to mention that a large chicken would have to have very strong muscle to walk making rather tough to eat.

Think of the eggs!

Not at all. This is one of my favorite films and I think of that kind of stuff all the time.