My biggest blooper in Skyrim was in the main quest. Supposedly you are to walk the 7000 steps up to High Hrothgar and the Greybeards. Well I missed the part about the steps and spent about two hours climbing up the other side of the mountain. Found out about the 7000 steps later when my girlfriend was playing, lol.
I was hunting deers near whiterun
Suddenly Vigilance, my dog, started flying over me, thinking himself a dragon
Suddenly I realize he was sitting on a butterfly
I wonder, can we do this too
Anyway, it was hilarious !