The latest edition of the Rules of Golf will keep players from being disqualified if a penalty is discovered after they have signed their scorecards.
Players who are not aware of a rules violation until after their rounds have been knocked out of the tournament because when the penalty is applied, they are guilty of signing for the wrong score. Now there is an exception to Rule 6-6d that says a player will not be disqualified for an incorrect scorecard if he was not aware of the rules violation when he signed the card.
The rules are updated every four years by the Royal & Ancient Golf and the U.