Here are 9 leaked image from "Animal House," the episode which is airing on Tuesday, September 4th. It looks like they are taken automatically at regular intervals in the episode, which means the dragonboarding probably appears at the beginning and the creepy blue halo appears at the end.
And here's the updated episode description: "As an approaching storm threatens Berk, Hiccup must work fast to make peace between the food-providing farm animals and the dragons."
Read more for the beautiful 720p image set.
UPDATE: 1 new picture was found! (Thanks Serimon!)
UPDATE 2: A new description for Animal House from mysanatonio.com
"In the Viking kingdom featured in the animated series
“Dragons: Riders of Berk” (6:30 p.m., Cartoon Network), the price of tranquility runs high. Inspired by the movie “How to Train Your Dragon,” “Berk” asks us to imagine a world where dragons and people have become friends. This seems like a plus, until the friendly giant lizards start scaring the barnyard animals. The kids know the dragons mean no harm and can be fun playmates — particularly while sledding down mountains — but try telling that to sheep."