Remember those skeletons Jack and Kate found in season one -- the ones Locke called "our very own Adam and Eve?"
Well, wouldn't it be cool if those skeletons were really Jack and Kate? Wouldn't it be cool if they got rescued as part of the Oceanic 6, and then tried to get back to the island, but they went the wrong way and went too far back in time, and then they were stranded alone on the island, and they found their way to this cave 'cuz they already knew about it from the future, and they had a white rock and a black rock to give clues to their future selves, and they died in the cave, and their bodies rotted, and they became the very skeletons that they found later on? Wouldn't that be cool? Wouldn't it?
Nope. Not if it made this list.