Another thing to check for are "Tank Traps" as we used to call them. It's a raod or trail that leads through a building. To an AI that is the quickest route.
Watch out for a similar thing with helos that will fly over the enemy as the shortest route.
I just had a helo retreat off screen with a full load after taking ground fire.
Also, riverine craft will "collapse" buildings on the waters edge, although I have not had one get stuck yet doing so. But as noted above, if you move 1 hex at a time, which is prudent anyway, then you avoid that problem.
In a battlefield there isn't anything valid as a "quick" path or "shortest" route.
You should always move your units using smaller steps because this way you control tactical manouvers.
The tactical redeployment is an action that most of the times needs to follow the unexpected way of approach.