Has a FIBA World Cup game ever ended 20-0?
It has. 20-0 has been a FIBA World Cup final 3 times in 2,041 games. The first was Brazil beat U.S. Virgin Islands on September 16, 2018; the latest was Iran beat Australia on January 1, 2023.
That makes 20-0 the 96th most common final score out of 1,178 that have ever occurred in FIBA World Cup. One point away, 21-0 has happened never and 20-1 has happened never. Nearly all of its occurrences fall between 2010 and 2039.