Maybe this is intentional - not a Chinese castle expert - but there appears to be missing bricks/ a hole in the battlements on the right side of the Shu castle. Assuming it should be symmetrical
Terrain is visible through the gap, Here’s what I assume it should look like on the right. I know it’s a minor nitpick
Wait I thought you were pointing that it was clipping through the walls
I Still cant tell whats wrong
I’m not exactly sure what you’re pointing to, but here is a closer image…
Are you talking about the patch of what might be green grass from the background here?
Or are you talking more about maybe an optical illusion where you think your circled brick is a 90-degree corner piece, but is actually a normal capping brick, imo, that just happens to visually line up with the floor to make it look like a corner?
If the grass, yeah, it seems odd grass is possibly showing through. But wow, how did you see it?
EDIT: After analyzing and re-seeing your 2nd post, I now think you mean the green grass showing through. As it showed snow in your other (snow) one. Okay, I got ya. Definitely could use a little brickwork there 
Such a mistake indicates the model wasn’t done by mirroring it, interesting.
Yeah it’s mainly the terrain showing through, snow shows it better.
I’d probably be better at the game if I weren’t staring at the units and building so much!