Has a FIBA World Cup game ever ended 84-82?
It has. 84-82 has been a FIBA World Cup final 4 times in 2,041 games. The first was Mexico beat Argentina on May 14, 1963; the latest was Spain beat Belarus on February 23, 2018.
That makes 84-82 the 44th most common final score out of 1,178 that have ever occurred in FIBA World Cup. One point away, 85-82 has happened 3 times and 84-83 has happened 2 times. At one point the score disappeared for 35 years, between 1963 and 1998.