Watching all six episodes in a row, a few things popped out a little better than the first time I saw them.
1) In "Anal Probe", there's a picture of a teenage girl next to Cartman's couch, which I didn't notice in any other episode (it may have been destroyed by the flaming kitty). Possibly his older sister?
2) Also in "Anal Probe", the chalkboard says "I am positive that Cathy (sic) Lee Gifford in older than she claims to be."
3) In "Weight Gain 4000", after the mayor, who is a woman, says "Ms. Lee Gifford", Chef says, "Thank you, Mister Mayor."
4) In "An Elephant Makes Love..." the genetic engineering kid is named Terrance, and Pip's real name is Phillip. Coincedence? Probably.
Aaron