None currently known.

Many prehistoric animals die on and off-screen. It is even implied by the narrator that some of the featured animals became extinct, which may be distressing to some extinct animal lovers.

Body parts of the Lystosaurus are scattered throughout the river in one episode.

None currently known.

None currently known.

The Anomalocaris looks alien and the close-up of its eyes may disturb some people.

Brontoscorpio and Pterygotus (both species of sea scorpions) may terrify people who have fear of scorpions, despite the latter not being a scorpion.

A giant carnivorous fish (Hyneria) hunting other fully-aquatic and amphibious animals may be intense.

A giant mesothelae spider may traumatize people who suffer from arachnophobia. However, the giant mesothelae spider shown in the program never existed in real life during the Carboniferous period, despite many arthropods existing during that time and growing much larger than today.

A young Edaphosaurus is hunted by a Dimetrodon mother. This may shock and upset some viewers.

The gorgonopsids (Inostrancevia) may scare children.

A pack of therocephalians (possibly Euchambersia) may terrify some viewers, especially since they're stated by the narrator to be venomous, and even more so than modern black mambas. Despite this portrayal, there's not yet any evidence of therocephalians of any species having venomous bites.