Here is some errata for 3W's Battle of the Alma. Some of it is from the 3W topic on GEnie, and the rest is from a personal letter from Rob Markham. One column shift.
Trails cancel the movement cost of slope and river hexsides.
A unit can change its formation at any time throughout its movement. It is legal to move in column, expend 4 movement points, and then change to line at the end of movement. Units which are disrupted in melee do not retreat. When units retreat, they change facing to reflect their movement. A unit advancing after fire combat cannot then melee against the retreating unit.