"that jacket is so September 10th" - it's said that everything changed on Septermber 11, 2001, so everything that didn't change is passé. Like intolerance of different lifestyles.
Butters' mom is seen giving Kyle a pedicure at the mall, so we now know what she does for a living.
Metrosexuals used to be called effeminate, emasculated, or sissies. Here's an article on metrosexuals.
Some behavior that is now considered gay used to be standard among kids. A sample: saying "good morning" to the teacher in pleasant voices and in unison, brushing one's teeth three times a day, nicely combed hair. Only the clothes are different from proper childhood dress of years gone by.
The shirt worn by Queer Eye For the Straight Guy's Kyan
is split between Randy (who has the Native American totem motif on a new background) and Cartman (who has the background design behind Marylin Monroe). Randy also has Kyan's hairstyle.
Mr. Slave is not present in Mr. Garrison's class this time, a fact confirmed when Mr. Garrison tells him about the kids' behavior in class.
catamite - a boy who serves as a receiver in pederasty (man-boy sex).
Jimbo's sexuality remains in question. In "It Hits The Fan," he was marked as gay by the fact that he wasn't bleeped when he said "fag," and in "Two Guys Naked In A Hot Tub" he was with Cameron, a bald burly man. But here he declines Mr. Garrison's invitation.
Well, we find that Jimbo is bald and Ned has curly hair.
Jimbo is drinking from a tiki mug.
Proof positive that white culture takes its cues from black culture: Mr. Garrison and Mr. Slave go back to their "flippity floppity floop" even though Chef wasn't serious about that term. :D
South Park is growing. Check out the new trains stationed there.
Looks like Trey is making an effort to sound more like a boy again. For a while people have noticed that Stan and Cartman's voices were deeper than expected for fourth graders. Here, they both sound as they should.
Jimmy's mother and Butters' mother both call their husbands Steven, even though the husbands' names have already been established as Ryan and Chris, respectively.
The crab people could be based on the Macra, the alien crabs in Dr; Who's "The Macra Terror"
Near the end of the episode, when the women face their men at the mall, Randy and Tom step forth. When they do, their bags seem to pass through the boys' heads. Randy's passes through Cartman's and Tom's passes through Craig's. Tom's right leg also seem to pass through Token. The best way to explain the effect is to look at Han Solo as he steps around Jabba the Hutt in the newer version of Star Wars: A New Hope, which includes the enhanced, formerly deleted scene.
Difference between the episode and trailer:
"Last year you children were all trying to be black, and now you're trying to be gay!" - In the trailer Chef said it in the cafeteria but in the episode he said it in the school hall.Mr. Garrison says "Now everyone is acting like a flaming queen!" in the trailer, but "Now every straight guy is acting gayer than me!" in the episode.