Has a World Cup game ever ended 19-0?
Exactly once. On November 24, 2000, Iran beat Guam 19-0, and no World Cup game before or since has ended that way. When it happened it was a scorigami, the first 19-0 in league history.
That makes 19-0 the 43rd most common final score out of 53 that have ever occurred in World Cup. One point away, 20-0 has happened never and 19-1 has happened never.