Possible Clues:

• 'Smooth Criminal' about one's point of no return
• River crossed by burning boats
• In piquet, the winning of a game before one�s opponent scores 100
• There's no going back over this working after creator of puzzle's spoken
• Polish trick to get across one ancient border
• Figure following stroke on river
• Line fatefully gone over
• Italy/Gaul boundary
• Caesar's river of decision