What could happen if I consume too much B12 energy? Specifically those 10, 000% B12 energy shots?

Vitamins. Simply play a part in the synthesis of cellular energy. B12 and Folic Acid are "members" of a team that all work together so there is no such thing as "b12 energy" on its own. B12 is a common deficiency so i presume that you are getting the shots from a physician.