Has a World Baseball Classic game ever ended 16-1?
Exactly once. On March 11, 2009, Mexico beat Australia 16-1, and no World Baseball Classic game before or since has ended that way. When it happened it was a scorigami, the first 16-1 in league history.
That makes 16-1 the 47th most common final score out of 80 that have ever occurred in World Baseball Classic. One point away, 17-1 has happened never and 16-2 has happened never.