Has an AFL game ever ended 71-13?
Exactly once. On July 17, 1897, Melbourne beat St Kilda 71-13, and no AFL game before or since has ended that way. When it happened it was a scorigami, the first 71-13 in league history.
That makes 71-13 the 3836th most common final score out of 6,607 that have ever occurred in AFL. One point away, 72-13 has happened never and 71-14 has happened never.