Question: What happens when the wrong player thinks they are east, and they roll the dice and break the wall .

Answer: If the wrong player initiates a game out of turn (rolls the dice and breaks the wall), the hand is played to the end, and the winner is paid. At the start of the next game, the rightful East starts the game. The player who began as East incorrectly skips one turn at being East.

Source: Mah Jongg Made Easy 2024, page 17, #5