Couple of things come to mind:
1) In a under 14's elim? final being held at Goolwa on a sunday a little old lady to proceeded to walk across the oval from the North Eastern pocket to the South Western pocket while the game was in play. Didn't alter her path, just kept on walking through as the game went on around her. It was found out later that she was going to church and had always crossed the oval to get to the church and wasn't going to alter course for a game of football.
2) Early days of night games at Strathalbyn and they were hosting Yankalilla. As both A grade teams are warming up out on the ground at their respective ends, the word comes out from the runners to the teams that there's been a major crash on one or the nearby arterial roads and that the Royal Adelaide hospital helicopter needs to land on the oval because it is most suitable spot; flat, vast and lit up like a christmas tree. So all players and spectators have to get off the oval. About 15 minutes later the helicopter comes in and lands at CHF at the scoreboard end spraying all in sundry with dry grass clippings. The Ambo drives out on the oval, delivers the patient/s and both it and the helicopter promptly leave the oval. The game was delayed by about 30 odd mins or so and Strath ended up winning the game.