Kids need frequent reminders that drugs are bad, m'kay?
We know that Mr. Kitty is female from "Cat Orgy," but that Cartman always calls her Mr. Kitty. Female cats don't produce concentrated piss like male cats do.
"fon to due" - combination of "fun to do" and "fondue."
"I have written up a bill that would make having a cat illegal." - China is ridding Beijing of its pet cats under the fear that many of them are carriers of diseases. Skeptics say that China is just doing this so Beijing looks immaculate during the Olympics.
Cartman having Mr. Kitty write a diary, and in an attic in the first place, is a reference to The Diary of Anne Frank, as Anne would address her entries to Kitty while she was hidden in an attic. Cartman taking in all those cats and hiding them, keeping the diary in mind, is a reference to Schindler's List. When Cartman goes to rescue Rufus and his kittens, he's dressed as Oskar Schindler. And like Oskar Schindler, Cartman reluctantly takes in more cats when he really can't anymore.
Gerald was cheesing until ten years before the present. Considering that Kyle is nine, or should be, it could be that Gerald stopped before getting Sheila pregnant, or more likely, stopped before they got married.
Kyle hasn't cheesed, but he's taken acid and chugged cough syrup. Not at the same time.
"Jewish Princess" could be a take on the derogatory term "Jewish-American Princess" (a pampered girl of Jewish descent, the daughter of wealthy Jews).
The woman's breasts are never fully visible to the viewer - they're either clothed, or something blocks the view from the TV viewer. Kenny and Gerald can see them quite fine, though. If the breasts are by themselves or built into the architecture, though, the TV viewer can get a full view of them.
The woman in the hallucination is based on Taarna, the warrior woman in "Taarna," the last story in Heavy Metal.
Gerald's press conference is modeled after that of Eliot Spitzer, who was forced to resign when he was caught doing something he promised to eliminate during his governorship: government corruption. The look on Sheila's face is the same one seen on wife Silda's face when Spitzer held his press conference, as the corruption involved a prostitution ring.
Several lines used in the first few seasons of the show make a return here, most notably, "you know, we've all learned something, you guys." ("You know, I learned something today.")
"Fermenting feces" - this refers to jenkem, the gas produced by fermenting feces in sewage water, in a bottle capped by a balloon, over a week in the sun. It's more potent than glue.