Loose Threads:

None yet.

Notables:

The title is a reference to "That was Then, This is Now", a book by S.E. Hinton about two boys who are growing up and apart.

Trent has a Korn poster in his room, so the earlier Helpful Corn reference may have been a play on Korn.

Willow talks about hemp processing, but growing hemp is currently illegal in the US, so they must import.

Ethan's comment about "peas" is a play on the old hippie slogan "Peace".

Jake and the hippies trying to levitate the Pentagon by positive energy brings to mind one of the weirder rumors that made the rounds. Supposedly, the Pentagon's odd shape is because it is being used to confine the demon Yog Soggoth (demons being confined in pentacles). This caused all sorts of strange attempts by various groups to do things to the building.

The Zappa record Trent and Jesse were listening to is "Weasels Ripped My Flesh." The song is "My Guitar Wants To Kill Your Mama"

As Daria and Jane are sorting the records into separate boxes, Daria picks up a sleeve which is clearly the Banana album - {Velvet Underground and Nico} (the name as well as front and back artwork are shown, and they got the design nailed).

Trent is aware of Daria's feelings now (symbolically "waking up" to them, just as he woke up from his nap)

In some scenes at the flea market, the words "collectable LPs" are  missing from Trent and Jesse's sign.

Mr. DeMartino is an Annette Funicello fan. She's best known for her appearances on "The Mickey Mouse Club" and 1960's teen beach movies, but she did sing a number of Top 40 hits.

Jake's transition from calling Coyote "man" to "pal" is a bit symbolic of Coyote's transition from hippie to ex-hippie.

Rock and Roll Randy was selling comics at the flea market.

Helen has punched out a cop.

Mistakes:

The clock in the Morgendorffer's kitchen show different times at different points in the dinner.

The clock in the Morgendorffer's kitchen run backwards during the  "flashback" sequences, it goes from 8:45 to 8:00.

Double Meanings:

None yet.