I ran some tests on my computer but I can't recreate your glitch. The unit in the civopedia, and the menu look fine on my computer. I checked it on low and high graphics settings as well. I can't figure out why it would show up differently in the menu and in the civopedia... I know that the civopedia uses different shaders then the normal game but this shouldn't have any effect on the head graphics...
Does anyone else have this problem?
(I would have replied sooner Wolfshanze but i had problems getting onto civfanatics earlier.)