Freeing pinned boats does have some associated hazards.  This is why we take our time to evaluate the best and safest course of action.  The first and most obvious is when the boat is freed, it will contain hundreds of pounds of water that is accelerated by fast moving current.  Riggers need to be especially cautious and probably should get away from the boat if feasible.  Avoid placing your feet inside the cockpit as this may lead to foot entrapment.  The haulers on shore need to be prepared as well.  The hauling line will soon get a great deal of force as well.  If simply pulling on the boat and it gets out of control, rope burn is one possibility.  This can be mitigated with gloves and especially a no-knot tag line.  An independent spotter is another great safety precaution.