Unlike other creatures in the series, the humans in this episodes were portrayed by actors rather than CGI and animatronics.
The prosthetic Neanderthal make-up took several hours to apply.
The Neanderthals were portrayed by no more than four actors. In shots with more than four Neanderthals, they were digitally replicated.
Contrary to popular belief, Neanderthals were not unintelligent creatures. In fact, their brains were slightly larger than those of modern humans.
Never seen are Spotted Cave Hyenas, despite being one of the most common fossilized predators of the Eurasian Ice Age. Although they are briefly mentioned by the narrator and after the Neanderthal-Mammoth hunt, hyenas can clearly be heard off-screen as the Neanderthals are finishing off their kills.