Dromaeosaurids (commonly known as "raptors") like Utahraptor and Dromaeosaurus were featured with no feathers, however when this show was made, the theory that they might have been feathered had already been crafted, and even confirmed by actual fossil evidence.
Every pterosaur (flying reptile) in the series folds its wings incorrectly -- sideways. The bone structure only allowed these animals to turn their hands outwards to the sides, rather than frontwards, and this allowed them to neatly fold back their long, wing-supporting fingers, but not to the side.
A recurring animation error throughout all of the episodes is how the body parts and muscles of the CG animals clip through each other while moving. Wrinkles and skin patterns appear and disappear, and sometimes strange bulges stick out of the animals, seemingly moving independently from the surrounding flesh. This kind of error is perhaps the most noticeable on the shoulder region of the Diplodocus, as the shoulder muscles and the upper part of their front legs "merge" and separate repeatedly at each step.