If you can remember eariler in the year a new Up character was revealed, which was the dog from Ratatouille. If you watch the Up trailer, you can see a stuffed dog in the corner of the girl’s room, that looks alot like the picture of the dog. But if the girl is’nt a main character, than how could it’s stuffed animal be? Maybe it was a main character, and they hid it somewhere in the movie. Of course Pixar would’nt hide a main character somewhere, as far as I know. Do you have any thoughts?
Err, I thought there’s already a thread for this topic. 
BTW, aren’t the main characters [spoil]‘Carl’ and ‘Russell’?![/spoil]
Killler123 is correct, we already have a thread for Pixar references in Up:
If you repost your question there, I’ll give it a shot at answering it.
Now that it’s on DVD we know all the answers 