I'm probably not looking hard enough. Where's the anatomy error? Is it the weird angle of her waist?
I believe it's a minor error in the arms. If you look at her right forearm, the artist drew it such that it looked like it was sinking into her breast, but it's a little too misleading. The left upper arm is the one that really gives it away though -- it isn't straight. The perspective suggests that she's leaning back, but it isn't completely correct.
That's what I could notice. This was a revision of post #2435330 that dk.senie updated on pixiv (he added a smoke effect and fixed the contrast a little bit), but it looks like it'll have to fight for its' approval. I was considering flagging the original, but it didn't look like a huge mistake in my opinion. The eyes, breasts, ass, and thighs are all still relatively well done.