It was a result of poor defense from Bayern side. Real simply outclassed Bayern on multiple occasions.
First and second goals which were scored on the header were simply the result of leaving Ramos unmarked, which Bayern defense should have kept marked. After them two blows, Bayern were shocked by brilliant counterattack by Christiano Ronaldo, who simply outruned David Alaba, it was really unexpected, and Bayern wasn't prepared for that counterattack, and at last that last but not the least one which really shocked me was that 'Free kick goal', it was almost like the 'wall' and 'Neuer' both were missing there.
Overall I would like to say that it wasn't simply Bayern's day.U_U