An SF character said SF is like a European city which is rather pretentious, but guess who has said the same thing? Michael Palin, in one of his travel books! (I think it was the Pacific Rim book) And Trey is a big admirer of the Pythons.
The farting was a reference to what? I think there is a form of Asian yoga or something that includes breaking wind.
Cartman being in SF wasn't very funny but I liked the joke about closing your eyes when talking.