Cards appear at several points during Inside Out, both in and out of Riley's subconscious, most prominently seen in the various attempts to build a full house of cards in Imagination Land. If you pay attention, however, it's clear this isn't any ordinary deck. The face cards feature Riley (as her own separate class, R) and her parents (as the King and Queen respectively). On top of being a nice little style choice, it's a subtle way of showing how the pre-teen girl views her family dynamic.