Right on the full line is a common breakage point, because the stamped line makes a natural fracture/fatigue point. So that leaves about a 1-1/2" long piece in the pan.
Maybe you could fish it out with a pencil magnet through the drain plug?? Or put a magnet on the bottom of the pan to "capture" it and just leave it there until some point down the road that you have the engine out or the pan off??