Before moving a unit, the path that is shown for movement is sometimes overly optimistic. A unit with a move of two can be shown to have three steps on plains for a single turn of movement or moving on a road is shown to take you farther in a turn than is actually possible. After clicking on the destination, the path updates and you see you won't get as far as you thought as the path updates and the last square turns from a green 1 into a yellow 2.
