 There is a scene after The Black has jumped overboard and Alec is in  the water yelling for help and The Black is swimming towards him.  Suddenly the horse begins to tip over, his head plunges underwater  and he starts to thrash in the water and his hooves are pawing in  the air. This was an accident due to the guide wires being used to  control the horse. Too much force was applied on the turn and the  horse went under, a serious cause for alarm on the set. To  everyones relief, the horse righted himself and popped up out of  the water just fine.