When the female Leptictidium picks up an insect and lets her litter smell it, watch closely. The animatronic Leptictidium picks up a cricket, and the computer-generated version holds an ant.
The Gastornis prop's beak is covered in blood while eating the Propalaeotherium, but the CGI version's beak is clean.
The head of the animatronic Ambulocetus model is noticeably rounder and its cheekbones less pronounced than the CGI version's.
The Leptictidium's animatronic model has noticeable differences compared to the CGI version. Its trunk is smoother and lacks wrinkles, and the hair around its legs is more bushy, whereas the CGI model's fur lays flush.
For Godinotia, the sound editors used modern chimpanzee noises, however this animal belonged to a far more primitive lineage of primates, similar to lemurs, so their vocalization would probably have sounded much different than an "advanced" chimpanzee's.
At the time of production, Gastornis was thought to have been predators of small mammals and this behavior is exhibited in the episode. However, several lines of evidence, including the lack of hooked claws in known Gastornis footprints and studies of their beak structure and isotopic signatures of their bones have caused scientists to reinterpret these birds as herbivores that probably fed on tough plant material and seeds.
When the baby Gastornis is attacked by the giant ants, the ants are the same size as regular ants (thus several times smaller than they should be).
During the scene where the Gastornis attacks the Propalaeotherium, watch the bird's foot as the scene goes into slow motion. The leaves disturbed by the foot still move at the same speed during the switch to slo-mo.
In some cases, the movement of the leaves on the ground does not correspond correctly with the actions of the animals. In other cases, the leaves aren't disturbed at all when the animals move through them.
In the shot with the waterfall in the background, when the Leptictidium mother looks to the side, the skin texture on her chest becomes heavily distorted.
As the Ambulocetus strides through the water into the lake, its front leg very clearly passes into the bottom.
When the mother Leptictidium jumps after the dragonfly for the third time, the outline of its fur becomes awkwardly segmented due to how its CG model contorts.
Though it makes for a dramatic scene, there is no reason for the Gastornis to exert itself by violently shaking the tiny Propalaeotherium around after it's caught it. One bite with its beak was enough to kill it.
In this episode, Ambulocetus, a water-going predator from Pakistan, appears in prehistoric Germany. While the narrator does state that it's a newcomer, it couldn't have swam all the way from Asia up to the forest the story takes place in.