What's going on?
When firing arrows which stick into terrain, namely the ground, there seems to be a relatively high chance that when the arrow unsticks itself from its target, the arrow will drop through the floor and off of the map.
How to Replicate:
Fire an arrow directly at your feet,
Wait roughly 8-10 seconds for the arrow to unclip from its target
The arrow will either fall to the ground OR fall through the floor and off of the map.
Here is a walk-through for clarity (link to gfycat video)
Perceived Impact:
Since this only happens when arrows stick into the floor, and the cost of arrows is relatively cheap, I don't see this as a pressing bug.
Additional Notes:
This does not appear to happen if the arrow sticks into targets, or into vertical, non-floor objects (ie: walls, Mystery Machine, etc.)
This bug increases in frequency the more vertical the arrow is.
This is not a 100% chance to happen, but in my testing it happens about 20-30% of the time.