Has an AFL game ever ended 50-20?
Exactly once. On July 18, 1903, Carlton beat Sydney 50-20, and no AFL game before or since has ended that way. When it happened it was a scorigami, the first 50-20 in league history.
That makes 50-20 the 3884th most common final score out of 6,649 that have ever occurred in AFL. One point away, 51-20 has happened 1 times and 50-21 has happened never.