Loose Threads:

None yet.

Notables:

Mr. O'Neill's talk about "the competitive and discouraging" aspects of grading is very similar to one of the cornerstones of the Progressive Theory of Education (the one that has held sway in US public schools since the 1950s), which finds objective standards very distasteful.

Mr. O'Neill wanted to be a gymnast, but couldn't master the high bar (he managed to break both arms).

Brittany is wearing a pig backpack... it looks exactly like the pig from the movie "Babe"... which is what Kevin calls her all the time.

Jake has had phone sex.

Corey (the obnoxious guy from "Esteemsters") reappears.

When Mr. O'Neill is about to read Quinn's essay, there's a student on the right of the screen who looks a lot like the recurring character "Judith" on "Third Rock from the Sun."

Quinn's essay compares schools to prisons, a fairly common comparison.
"There are only two places in the world where time takes precedence over the job to be done. School and prison." --William Glasser

The theme of school as prison is an ironic one considering the conversation between Helen and Ms. Li in the previous episode (The Daria Hunter). Which includes the line: "It's interesting that you draw a distinction between school and prison because from what I hear you run the one pretty much like the other". Apparently she does.

When Quinn's essay gets put on the Morgendorffer fridge, Daria notes that it's "quite a wall of distinction." It must be just for Quinn's stuff... the only other things on it are a kindergartner's drawing and a DMV citation.

The school paper is the "Lawndale Lowdown".

Quinn's locker contains a teddy bear, a list of Fashion do's and don'ts, and a ribbon in the shape of a 'Q.'

One of the nerds at lunch is the kiss-up from Mr. O'Neill's self-esteem class in "Esteemsters."

When Quinn encounters Daria in the lunchroom, she's wearing a hat and sunglasses, which is particularly similar to the getup Mrs. Krabbaple wore in "The Simpsons" when she and Principal Skinner were first dating.

Pay close attention to the guy in the background when she's there: He moves along the cafeteria line, then stands still at the inanimate cashier.

Brittany calls Kevin a high-school Casablanca. She was going for Casanova, but since Casablanca is considered a very romantic movie she probably got close enough for her.

Stacy writes poetry.

Albert Camus was a French Existentialist."At the heart of all beauty lies something inhuman, and these hills, the softness of the sky, the outline of these trees at this very minute lose the illusory meaning with which we had clothed them, henceforth more remote than a lost paradise . . . that denseness and that strangeness of the world is absurd."
Daria's definition of Existentialist for Quinn is very close.

The black guy behind Quinn in the cafeteria (in the Fashion Club Confrontation scene) is reminiscent of Tuvok from Star Trek: Voyager.

Daria scares the Fashion Club (and Joey, Jeffy, and Jamie).

For the Quinns of the world, Pavlov was a psychologist who did conditioning experiments on dogs. He managed to get them to expect dinner and start drooling whenever he rang a bell, food or not.

Joey, Jeffy, and Jamie make the comment "A thousand times yes" when speaking to Daria. This is a reference to an old Betty Boop bit, "No! No! A Thousand Times No!!"

Mistakes:

The Morgendorffer's clock didn't have any hands.

Jake's money is blue.

The school newspaper changes color.

Daria's locker is missing its door when Kevin and Brittany are talking. When the door is there, the picture on it disappears when Daria closes it.