When Is It Too Late to Appeal?

[Spence]

Bottom of 7. Tie game. 1 out. R3.

Short fly ball to LF. Runner tags. Beats the throw game over.

Players are going through the post-game handshake line. Head coach of defensive team goes to the umpires who are starting to leave the field and appeals that the runner left early. Umpires agree. Double play. Inning over. Extra innings.

The question has arisen as to when is it too late to appeal in this case? Is there something about players still being on the field? Umpires still on the field?

BTW this is FED.