Has an AFL game ever ended 71-51?
It has. 71-51 has been a AFL final 4 times in 16,622 games. The first was Carlton beat Geelong on August 19, 1911; the latest was Richmond beat Collingwood on August 3, 2001.
That makes 71-51 the 947th most common final score out of 6,607 that have ever occurred in AFL. One point away, 72-51 has happened 2 times and 71-52 has happened 4 times. At one point the score disappeared for 44 years, between 1911 and 1955.