Al Gore's obsession with ManBearPig is supposed to be a spoof on Gore's high profile activism regarding climate change, as Parker and Stone did not believe in it at the time of the episode. The episode Time to Get Cereal (2018) can be seen as a sort-of apology to Gore as the topic is taken much more seriously, as Parker and Stone have since changed their opinion on the issue.
The creature, ManBearPig, may have been inspired by the film Extra Terrestrial Visitors (1983), later re-named Pod People. The film is about an alien monster that lands on Earth and attacks some poachers and teenagers. When the poachers confront the monster, one remarks, "Looks like a cross between a pig and a bear." The obscure film became more recognized when it was riffed in Pod People (1991), an episode of Mystery Science Theater 3000 (1988).
In the disappearance of Dennis Martin, a six-year old boy who went missing on June 14, 1969 in the Great Smoky Mountains National Park in Tennessee, there were several witnesses who claimed to have seen some man-bear-pig-like creature abducting the child. The creators might have gotten some inspiration from this story.
The synthesized score and POV shots used as Al Gore, dressed as ManBearPig, approaches the boys in the park are heavily influenced by the werewolf attack scenes in Silver Bullet (1985).
The bottle that Cartman holds as he eats treasure is spelled wottur