I've been slowly playing my way through UQM HD Remix, and noticed that the Syreen appear to be missing a breast:
It looks especially bad when animated - what I suspect was supposed to be a 'heaving bosom' instead becomes some sort of awful-looking hole in the chest.
It bothered me enough that I created a mod to fix this. While I don't consider myself a great artist/photoshop wizard, I still think it's an improvement.