Q: If a player forgets to say “Jumanji!” and throw up their hands when they meet the Goal conditions, what happens?

A: We tend to be quite lenient on this one. It’s for fun, not for cutthroat games. So we’d say, if someone notices that the player meeting the Goal has forgotten to throw up their hands and say “Jumanji!” that the other players should simply remind them to do so. The winning player should consider it a close call!

If nobody at all notices until the next game has begun, then you just get away with it.