Your Friend the Rat (home media; about 12 minutes)
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This was first released in 2007 as a bonus feature on the DVD of Ratatouille, to which the short is related. It's also available on the Pixar Short Films Collection, volume 2. The framing device is in CGI, featuring Remy and Emile, two rats from the main movie. They show an educational film which is in various animation styles, about the relationship between rats and humans throughout history and different cultures. And they end with a song about their hope that rats and humans will eventually learn to live together peacefully. And I don't know what else to say, but the short is fairly amusing.