Easter egg: "The Simpsons: The Complete First Season." On disc 3, go to the special features menu. Click "next" to go to the second page. Highlight "Some Enchanted Evening Script" and press left to highlight Bart's T-shirt. If you press enter on your remote, you get to watch an ABC news story on how elementary schools ban Bart Simpson T-shirts.
Easter egg: "The Simpsons: The Complete First Season." Go to the special features on disc 3. Go into 'Art of the Simpsons' on the second page. On that menu, highlight 'Extra Features' and press left to highlight Bart's comic book. If you press enter on your remote, you get to view a gallery of old magazine covers.
Answer: I'm not sure if this is the one you're thinking of, but an episode of "Ray Bradbury Theatre," called "A Sound of Thunder," dealt with a similar matter: a group of hunters travel back in time to hunt dinosaurs, only to find things have changed when they get back because someone stepped on a butterfly.
Xofer