John Christ

In the opening scene, Scraps hears a high-pitched whistle, as if it's a dog whistle and he's an actual dog. As such, Sid is supposed to not be able to hear it. However, Scraps' reaction is unmistakable - particularly in light of their being able to talk to each other, meaning should understand his words - that he is hearing a sound which is distracting and driving him nuts, yet Sid seems determined to take it as being a reaction to what he's telling Scraps. Once is funny, after that it is absolutely unrealistic for Sid to keep mistaking this reaction.