The placement of the shadows changes in separate shots when the male Dimetrodons arrive to steal the female's kill.
Multiple shots of the mother Dimetrodon digging her nest are repeated, and the clouds in the background remain the same despite the scenes supposedly taking place months apart.
When the two Dimetrodon fight, the clouds in the background shift position from day to evening, but when it turns night, the clouds are stationary, revealing that the night sky is just the same background re-used, darkened and tinted blue.
Petrolacosaurus couldn't have evolved into Edaphosaurus, since it was a diapsid, a reptile that belonged to a completely different animal lineage than Edaphosaurus (a synapsid).
The Mesothelae spider injects black venom into its victim, however spiders are known to have clear venom.
Both the Petrolacosaurus and Dimetrodon eggs are shown to be hard like dinosaur or crocodile eggs, which are animal groups that evolved far after the time of the episode. They probably had soft-shelled eggs like their closer relatives, lizards and egg-laying mammals.
As the two female Dimetrodon clash, you can see very briefly that the head of one of them passes halfway into the side of the other.
When the female Mesothelae spider lunges after the Petrolacosaurus, there is an upward-jutting object ahead of her, and the shadow she casts on it is flattened, as if being cast on regular ground.
When the Dimetrodon appears, you can still see the Sun's rays shining even after it has blotted out the Sun itself with its large back-sail. Normally, when the light-emitting object is covered, its rays also "disappear".
The Arthropleura keeps making clicking sounds with its pincers, even though they never actually come into contact.
One shot shows a pair of Edaphosaurus youngsters playing. They are in the shadow of a tree, yet the tree only casts shadows on the ground, not onto their bodies.
As one of the Edaphosaurus is shown laying down, there is a large rock under its tail. The shadow the animal's tail casts on the rock has the same color as the shadow on the ground, yet the rock itself has a much darker shade, meaning the shadow upon it should be darker as well.
As the female Dimetrodon starts eating the Edaphosaurus carcass, for a moment the movement of her head is reversed, creating a jarring animation effect.
Edaphosaurus had already gone extinct by the time Dimetrodon evolved, thus the latter couldn't have hunted the former.
Often the show's animals roar or make noises when it makes no sense. When the Dimetrodon sneaks up on the Edaphosaurus, it dramatically snarls despite being an ambush predator. Later when the amphibian sneaks up on the female Dimetrodon guarding her nest, it bellows at her, which would blow its cover.