Has an AFL game ever ended 42-13?
Exactly once. On July 10, 1897, Essendon beat Carlton 42-13, and no AFL game before or since has ended that way. When it happened it was a scorigami, the first 42-13 in league history.
That makes 42-13 the 3836th most common final score out of 6,607 that have ever occurred in AFL. One point away, 43-13 has happened never and 42-14 has happened never.