This is an easy one! Almost like the spider web question/image
If you look closely, the flag on the top right of the bus is facing forward.
Now that either means the wind is blowing it forward from the rear of the bus (and the bus is standing still), Or the bus is moving backwards, blowing the flag forwards.
However, a close look at the wheels reveals that the bus is indeed moving (motion blur)
Therefore, the bus is moving backwards