When D.J. tells Jesse he doesn't have to take the rap for her, she puts her hand on his elbow. It then cuts to a closer angle and her hand is not there.
When Stephanie brings Comet after he throws up, while he's lying down Stephanie goes to sit on the ottoman, you see his front paws and there's nothing on them. When Becky finds out he ate the "Silly Doh" she looks at his paws and now suddenly there's blue them.