Has a FIBA World Cup game ever ended 81-41?
Exactly once. On February 22, 2019, Senegal beat Rwanda 81-41, and no FIBA World Cup game before or since has ended that way. When it happened it was a scorigami, the first 81-41 in league history.
That makes 81-41 the 475th most common final score out of 1,178 that have ever occurred in FIBA World Cup. One point away, 82-41 has happened never and 81-42 has happened never.