An easy way to cultivate kid critiques - is to have them watch or read / watch different versions of the same story. For the toddler set this could be cartoon versions of familiar tales (cartoons are ripe for this - Christmas Carol, Jack and the Beanstalk, etc.), or for the older set, various remakes. Talk about what worked and what didn't. Compare and contrast.
And now for the Star Wars set, there's an ambitious Star Wars Fan movie (written, acted, produced by fans) that's available for download at the link below (HT: collision detection). Because it's a big file, you'll have to either use Bit torrent file sharing, or be patient with the conventional download as a quicktime movie. It's amazing. They even made some "Behind the Scenes" clips. Bravo! Maybe even movies can become an "interactive medium" like the blogosphere.
Star Wars Revelations