What should a referee do if a player not listed on the game roster scores a goal?

When a player who is not on the official game roster scores a goal, the goal is nullified and the game does not continue with that player's involvement. This is because all players participating in the game must be properly registered and listed on the game roster for their actions, including scoring goals, to be valid. If a player not on the roster participates and scores, it raises questions about the legality of their participation and the integrity of the game.

The referee's responsibility is to ensure that the match is played according to the rules, and allowing a goal from an illegal player undermines the fairness of the competition. Thus, any goals scored by a player not on the roster are considered invalid, and the game would need to continue without that player involved in future play. This upholds the standards set forth by soccer governing bodies regarding player eligibility and roster integrity.