The general color scheme of the movie's world is greens and light purples, and the clothing of multiple characters shows how their personalities mesh with this world:
Sally, the rule-stickler sister, is clearly dressed in the colors of the world, showing her obsession with conforming and following rules.
Conrad's clothing is exclusively a bright orange with yellow undertones, which clashes and throws off the coloration of the rest of the world. This shows his difficulty with following rules and behaving at the start of the film.
More subtly, their mother Joan wears pink, showing that while she is able to blend in with the rest of the world and be a hardworking mother, she shares some of her son's more rebellious traits and doesn't wholly conform.
Larry, their neighbor, shows the two sides of his personality with the clothing he wears.
His purple suit, yellow-green tie, and purple Palm PDA in his first appeance present the false image of a functioning member of society he keeps up around Joan. His arrogance and belief in his superiority is highlighted through this outfit being more formal and refined than any other character's.
His more casual clothing, which he wears for the rest of the film, are a faded green jacket, bright yellow sweatpants, and white undershirt: the green is a less bright one than the rest of the world, with together with his unemployment shows failed attempts at conformity, while the extremely casual pants and shirt show his true nature of laziness, greed, and entitlement.
If the existence of the non-anthropomorphic Nevins (as well as the other dog named Frank beside him during the scene where the Cat scares him away) implies the existence of regular cats and dogs in the film's universe, how would a small, regular house cat react if it saw a giant, talking humanoid cat wearing a hat?
