Has a FIBA World Cup game ever ended 90-50?
It has. 90-50 has been a FIBA World Cup final 3 times in 2,041 games. The first was Lebanon beat India on February 26, 2018; the latest was Belarus beat Albania on November 26, 2020.
That makes 90-50 the 96th most common final score out of 1,178 that have ever occurred in FIBA World Cup. One point away, 91-50 has happened never and 90-51 has happened never. Nearly all of its occurrences fall between 2010 and 2039.