Has an AFL game ever ended 91-90?
Yes. AFL has seen a final score of 91-90 6 times. It first happened on July 13, 1940, when Geelong beat Carlton, and most recently on July 20, 2003, when Fremantle beat Adelaide.
That makes 91-90 the 342nd most common final score out of 6,607 that have ever occurred in AFL. One point away, 92-90 has happened 6 times and 91-91 has happened 1 times. At one point the score disappeared for 36 years, between 1967 and 2003.