"We'll pick up with Clyde's speech about lesbian cheerleaders..." - refers to the recent (November 2005) story about two cheerleaders found having sex in a women's bathroom stall.
Daywalker - from Blade, a half-vampire with the ability to walk around unharmed by the light of day. Cartman compares redheads to vampires, and people with some redhead features to daywalkers.
Rearrange the first three letters in "ginger" to see Cartman's treatment of then in a more significant light. And then see this movie: 1970's Watermelon Man, a comedy in which an extremely bigoted white man finds out the hard (and somewhat humorous) way what it's like being a black man, firsthand!
This plot has been used many times before and since.
Token is wearing a dark purple shirt and lighter pants when he's doing his oral presentation, but his normal clothes when the class leaves for lunch.
It's interesting to see Token join the majority in kicking the minority redhead out of the cafeteria.
Déja vu: Cartman leading the redheads across the playground recall Cartman leading the townsfolk through town in "The Passion of the Christ" and of the kids marching through town in "Chinpoko Mon."
Cartman's mission is against non-ginger kids. Non-ginger adults he leaves alone.
Kyle is wearing his navy-blue pajamas under his coat from before he and Kenny knock on Stan's door to the moment they have to run away from the gingers. Right after Stan says "Run, dude, run!", Kyle is wearing his regular clothes, with his coat closed.
The only Airport Hilton I know that looks like the one in the episode is the one by the Burbank Airport northwest of Los Angeles.
The entire ginger convention in the Sunset Room at the Airport Hilton was a reference to the Roald Dahl book "The Witches." In the book, the witches were working on exterminating children "secretly" in a hotel convention room, same with Cartman and the gingers exterminating all non-gingers.