Question:
In a Finals game, at the beginning of the second half, team “A” kicks off.  Unbeknown to the CR and team A’s coach, 10 players are on the field in a 9v9 maximum player count.  Within 60 seconds team “A” scores a goal against team “B.”  It is determined that the extra player touched the ball in the transition, assisting in getting the ball into team “B’s back third and ultimately scoring the goal.  Team “B”s coaching staff notices the anomaly and brings it to the CR’s attention.

Does the goal count?

USSF answer (November 20, 2008):
No, it does not. The Laws of the Game are explicit — and it would make no difference if it were U9, U19, or adult professional players.

Goals scored with an extra person on the field of play
If, after a goal is scored, the referee realizes, before play restarts, that there was an extra person on the field of play when the goal was scored:
- the referee must disallow the goal if:
– the extra person was an outside agent and he interfered with play
– the extra person was a player, substitute, substituted player or team official associated with the team that scored the goal
- the referee must allow the goal if:
– the extra person was an outside agent who did not interfere with play
– the extra person was a player, substitute, substituted player or team official associated with the team the conceded the goal

It is clear from your scenario that the extra player interfered in play, which suggests that the referee’s decision should be no goal, follow the restart guidance given in the Laws. That is, provided that the game had NOT been restarted with the kick-off before the extra player was discovered. If the game had been restarted, life is hard and the goal counts