Actually, it would be very easy to think of facts that would disprove evolution.
Off the top of my head, I can think of , let's see...God appearing and invoking a bunch of new species, a new species appearing overnight without ancestors, or shadowrun's "goblinisation" when human kids turned into elves, goblins, trolls and such en masse when they hit puberty. (only works if the humanoids are not able to have kids together, though,otherwise you fail to meet the speciation definition)
of course, to disprove that darwinian evolution ever happpened, you'd have to prove that the new species-creating phenomenon was the only one working all along
Good luck with that
btw, when we discovered mitochondrial dna, we could have had a refutation of the ToE if the mitochondrial phenotype group borders had been significantly different than the host phenotypical group borders. They are not.
in plain language: mitochondiae are monocellular organisms that live in symbiosis with our living cells (human and animal). They are basically our cells'power plants(we can't live without them), but they have their own dna code. And when two individuals or species have common ancestors, so do their mitochondriae (since they don't leave our cells). had significant differenczs been found between species' "family trees" and their mitochondriae's, we'd have had to rethink the toe pretty badly.