The Duck card has no effect on the Movie but, when it comes out, all players must say "Quack !" at the first Duck, and "Quack ! Quack !" at the second one. The PPM is free to decide what to do with those who didn't follow this rule !
On the other hand, the Machiavellian PPM - having all the rights - can decide to play in "HUNGRY DUCK" mode: the Duck eats an Earthworm already present in the Movie, thus cancelling his effect.