Diplodocus held its neck in a slightly higher position than shown in the series.
Diplodocus was probably not the longest of all sauropods as stated. There were other sauropods longer than Diplodocus, such as Supersaurus.
There is no evidence for an ovipositor in Diplodocus. It was pure speculation by the creators of the series, who based it off of turtles. It is most likely that large sauropods preferred to lay their eggs while laying on the ground, with their cloaca close to the ground of the nest. The ovipositor hypothesis was an attempt at trying to go around the believed problem of having sauropods squatting to lay their eggs, but in reality, sauropods, even the largest ones, could lay down on the ground just fine.
There is slight shrink wrapping on the heads of Diplodocus, Allosaurus, Stegosaurus, Brachiosaurus, and Ornitholestes. In reality, the skull openings would likely not be externally visible.
Sauropods like Diplodocus are believed to have had more soft tissue around their necks.
The nostrils of the Diplodocus and Brachiosaurus are located towards the back of the skull. However, it is now believed that the animals' nostrils were actually located much farther forwards on the skull.
The feet of the Diplodocus and Brachiosaurus are more elephant-like, whereas the feet of the real animals had metacarpals that were positioned like pillars in a semicircle, creating a hollow back of the hand that was ideal for supporting the animals' large mass.
The large claw on the front feet of Diplodocus is missing from the model, as are the three large claws on the hind feet.
Ornitholestes didn't have a nasal crest. It was thought to have during the production of the show, however, due to the holotype specimen having a broken nose.
Ornitholestes was likely covered in feathers, based on its phylogenetic position, which did appear in the companion book. However, the show itself does show some primitive feathers displayed in some portions of the body, in the form of quills.
The head of the Ornitholestes model is slightly too large compared to the rest of the body.
The lower jaw of Ornitholestes slightly turns down, which is not seen on the skull of the model from the show.
Ornitholestes is now thought to have had sickle claws and retractable second toes like those of dromaeosaurids due to its recent classification as a maniraptoromorph. This would make it an early maniraptoran.
Ornitholestes and Allosaurus could not pronate their hands.
Anurognathus were micro nightjar-like insectivores, and there isn't any indication that they behaved like modern oxpeckers. Its anatomy in the show is also very inconsistent with the real animal, with a typically elongated neck, deep skull, small wings that fold in from the sides, too pointed wingtips, and a too-thin coat of pycnofibres.
Anurognathus didn't live in North America, only in Germany, although there are other pterosaurs from the Morrison Formation, such as Mesadactylus and Kepodactylus. This error was fixed in The Complete Guide To Prehistoric Life.
The head design of the Allosaurus is inaccurate; the crests are placed right above the eyes, when they were actually further down the skull, the small ridges in front of the crests are completely missing, and the snout turns down at the end, whereas the snout remains straight at the end in the real animal. Although this is still debated, it is also likely that, like many non-avian theropods, Allosaurus would have had immobile, lizard-like lips that would have covered its teeth when its mouth was closed. These errors were mostly corrected in The Ballad of Big Al, although the lip issue still remains.
Allosaurus may have been solitary hunters as opposed to the hunting pairs seen in the episode. It is possible hunting mobs would have happened, with no hierarchy whatsoever, but once they gathered to feed together, there could have been heavy competition. But it is also possible that they hunted in pairs.
Allosaurus is said to be the top predator of its age. In reality, the top predator of the Late Jurassic Morrison Formation was the much larger Torvosaurus, a genus of megalosaurid dinosaur.
Allosaurus is now thought to have delivered a muscle-driven bite to prey animals. In the episode, however, the Allosaurus is shown killing a baby Diplodocus by biting its neck like a Tyrannosaurus rex.
The Brachiosaurus model is based on Giraffatitan, which has been classified as a African species of Brachiosaurus at some point in time, due to it being much more complete. Because of this, the Brachiosaurus model is slightly inaccurate. In reality, Brachiosaurus would have had a longer and deeper torso, a longer and taller tail, and would have carried more of its mass on its forelimbs.
Brachiosaurus weighed between 28 and 58 tons, not 70 tons as mentioned in the program.
The raised bump on the head of the Brachiosaurus model is somewhat thin. In reality, the bump would possibly have more soft tissue around it.
Brachiosaurus is stated to be "the l
