The symbology will need to be changed from the output polyline to any arrow of choice so that the flow direction can be determined. Due to the cell by cell processing nature of this tool it is advised ...

If you are a MythBuster, the best option is to actually shoot an arrow straight up into the air and measure ... there is a force pushing back in the opposite direction of the object's velocity.

The blue dot and direction arrow in Google Maps represent where you are and what direction your device is pointing in. A minor update to the Android app today changes the arrow to a shining blue beam.