And someone said to me once that olives disprove the MWT - their reasoning is as follows: A person in one reality eats an olive, and in another, she does not. There should then be, according to my friend, a world where she eats all of an olive bar one molecule, another where she eats all of an olive bar two molecules, all the way to eating just one molecule of an olive. Since we NEVER hear of anyone eating just one molecule of olive, the theory goes, that must mean that MWT is not a valid model of the Universe(s).
I actually think that kind of proves it. We've pretty much established that our Universe is a quantum one - that is, it's not a grey goo but discrete lumps which are only ever divisible into other discrete lumps. There's no Universe where a person eats a string of a quark of a particle of an atom of a molecule of an olive, either. And no Universe where she eats an olive tree, either. Quantum mechanics therefore will pretty much limit what alternatives branch off at any point.
Also - we - that's you and I - are in a particular branch of the MWT Universes where perhaps olive quantum division isn't the norm. So it stands to reason that we will see very few cases of anyone eating her olives one subatomic particle at a time in this branch.
One more thing I always consider when making sweeping statements like "Many Worlds Theory is a crock" and that is that as far as we can establish, the Universe is infinite, and so is Time. By definition, that means that everything that we can imagine must exist *somewhere* in this infinity of possibilities. Not just once, but an infinite number of times over.
And that means that there has been, or will be, or is, somewhere in the Universe, a place where MWT holds true. And once it's true in that spot, it will be true all through the Universe. It's freaky to imagine that this has already happened at least once, when at some point in the Universe, a Universe decided to exist... Our question shouldn't be "what branch of the multiverse" but "why this one?"