I don't know if this is intented, but i retreated with trip on and heavy armor in hand and i couldn't move. It zoomed on both the encumber and trip before deciding to let me sit still. The char who had the heavy armor and trip attachment also played the retreat card. On another occasion, heavy armor reduced my retreat movement to 2. I think retreat should be unaffected by encumber since it is push and it shouldn't matter which character played the retreat. A bug?