I looked through a few pages and didnt see something like this, so sorry if there was.
Out by Karthspire (and within an arrow shot of a dragon mound) for the main quest, i ran into a Blood Dragon and it of course decided to try and kill me. After I got it to about half health, it went up against a mountain/stream/waterfall close to the mound it came out of and glitched into flying in tight circles. It eventually wound up flying in circles underground, then as i got close to it to see if i could still do anything, it flew straight up then crashed into some ground, where i killed it. so yeah, dragon glitched into tight downward spiral and kept flying underground. by dragon mound around karthspire.

i'm sorry but that sounds like the funnyest glitch ever. well next to sending dragon bones flying.

I had a blood dragon last night actually circle around me (near the northern shores above Solitude) and then swoop into the ocean and then come back out... sounds cool but once he hit the water it was lookin kind of glitchy and not fluid at all. Still able to kill him but figured I would make mention because it looked strange..