When must the offense make known the discovery of an illegal player involved in a game-ending double play?

The correct context for this situation is that the offense must make known the discovery of an illegal player immediately after the play, but before all infielders cross the foul lines. This requirement is tied to the integrity of the game and the enforcement of rules regarding eligible players. Making a timely announcement ensures that the opposing team is aware of any violations as soon as possible, allowing the situation to be addressed before the game proceeds further.

If the offense waits too long, such as after the game or during the next inning, it creates difficulties in retrospectively addressing the issue since the flow of the game continues and players may change, leading to potential confusion and an inability to rectify the situation. Thus, the specific timing mandated by the rules underscores the importance of addressing the legality of players immediately following a play that could affect the outcome of the game.