If you haven’t seen X-Men: Days of Future Past you might want to skip this (or don’t, what do I care) because all of these Easter eggs are kind of spoilery. Awesome, but spoilery. Maybe bookmark it for later. For the rest of you, prepare to have your mind blown at least once and probably more.
Related: All 38 times Mystique transformed into another person in an X-Men movie
H/T Blastr