You should pay more attention to the movie if you watch it again. For starters, Brolin is a CIA agent and Del Toro is the title character, and they are masquerading as defense contractors operating a joint task force.

The weirdest thing is that I've just not seen it brought up anywhere. I did read that Docter originally wanted them to be changing colors, but they felt it would be too confusing for the audience.

I'm wondering if they thought the driving/positive emotion was depicted as a blonde white girl (angelically glowing) that people would accuse them of being culturally/racially insensitive or something, so they felt the need to make her more "cartoony." Maybe there's a symbolic reason. I don't know.

Ever since I've read that each character/emotion is associated with a color — Fear (purple eyebrows/eyes), Disgust (green hair/eyes), Anger (fiery hair/red [or brown] eyes), and Sadness (blue hair/blue eyes) — the appearance of Joy has been nagging me. I've heard her described as "golden yellow" but she wears a green…