If you shoot an arrow on top of a repeater and then power that repeater, the arrows bounce as if they just landed.
How to replicate:
Step 1) Put down a repeater with a button near it so that the button powers the repeater.
Step 2) Shoot one or several arrows on it's top.
Step 3) Press the button.
Step 4) Watch the arrows bounce and make sounds.

Worked with 1.8 arrows and also works with new snapshot arrows.