Oh Derpy...

Doctor Whooves and Derpy. One combination that almost guarantees shenanigans of ultimate hilarity and adorableness. This time, somehow, they took a train with them.
So...I was deciding what color the engine should be. I settled on dark blue and white. Then I realized those are the colors of the Tardis. Unintentional yet kindof cool...anyway, the number on the smokebox, "3", is also a reference to time travel. Can anybody guess how? ;D