Most obvious error the AI makes is it can't handle the difference between artillery and infantry. Many a time I have watch the AI charge my lines with limbered artillery.
It also has a problem with leader handling in that it tends to leave leaders wandering around alone or in the front lines where they get killed. Many a game against the AI, which really only do for a quick look at the campaign scenarios, I have taken out Grant or Lee because he was wandering around in front of the infantry.
Worse logic problem it has is that the AI isn't situationally aware. It has no problem advancing a brigade or division with short frontage and no flank protection so it can be easily surrounded and wiped out. But this is a tough one to fix.
So all you have to do is link up DeepMind to the game to play the other side.
