When Hutch reveals his identity to Ernie Silvers, and whilst making a call on the hotel public telephone, he removes his (rather unconvincing) false moustache. In the next shot, the moustache is back on his face again.
Not only are viewers supposed to believe that cops would use valuable resources (time and money) to play a game, when Hutch phones Starsky, instead instantly of telling Hutch that his life is in danger due to soup ingested laced with botulism, Starsky merely tells him that Hutch won, and to give up the game, without providing a reason as to the urgency of stopping their silly game.