Wierd o.O , looks like a variant of the glitch where an object that you exploded freezes in place and loses velocity. I haven't experienced the glitch I mentioned, but I've seen it mentioned a few times around here.
The wierd part is that the moon was already exploded.
Also, did the timestep suddenly change? It didn't look like it, but just asking as you hid the interface.
Using iPhone ATM, but when I get back home, I'll see if I can reproduce the glitch. Maybe observe a sudden velocity change.
Oh yea, when I was messing around with exploding earth in bounce mode, I tried to set the velocity to zero, but it just ended up with everything launching and forming a cube shaped cloud. Not sure if that is related, although I think what I observed was more like a rubber band snapping, to use the analogy.
Edit: how many pieces did you explode the moon into? It might not matter, but I'm asking for the purposes of reproducing it. Unless you've got a save available.
Edit2: I think I've figured it out, you have your timestep too high. It could be a glitch involving the timestep and auto because when I put it on auto and have it in the green, it worked fine, but when I put it over to red, I saw what you saw, however your accuracy/speed indicator shows as green.