Has an NBA game ever ended 90-78?
It has. 90-78 has been a NBA final 30 times in 77,318 games. The first was Baltimore Bullets beat Indianapolis Jets on December 2, 1948; the latest was New Orleans Hornets beat Boston Celtics on January 16, 2013.
That makes 90-78 the 768th most common final score out of 3,189 that have ever occurred in NBA. One point away, 91-78 has happened 27 times and 90-79 has happened 37 times. Nearly all of its occurrences fall between 1980 and 2009. At one point the score disappeared for 42 years, between 1954 and 1996.