First of all, I'd like to say that this game has very good support, and this site apparently is the best place to get to know everything you want to know about C&C:A game.
FAQ is constantly expanding and updating, so now it is really very seldom in-game situation when you do not know how to resolve things.
But I came across such situation today.
The situation was like this:
My opponent has warriors unit stuck between fordable river just behind this unit and my heavy cavalry in front of it. I attacked this warrior unit with my heavy cavalry and rolled one flag, so this warriors unit was forced to retreat one hex straight into the river and lost one block because he could not complete his retreat movement. Then I made momentum advance with my heavy cavalry and get my cavalry in position next to the enemy warrior unit in fordable river. I decided to conduct bonus close combat against the same warrior unit and rolled two flags.
And here the question comes: should this warrior retreat 4 hexes, or they could not retreat, because they already retreated in fordable river in this turn and have to stay here, and so they are forced to lose 4 blocks and became eliminated?

Sorry for lengthy post, I just could not explain situation shorter.