Find a fossil of a modern mammal in a one billion year old rock layer. That would pretty much falsify evolution. Find a new species of life that doesn't use polypeptides, polysaccharides and polynucleotides as its basic biochemical molecules. That would also do it. Find a fossil that shows evidence of having both mammalian and avian characteristics. That would at least falsify the modern theory of the interrelationships of life.
Nice post.