- Please keep these annotations SPOILER-FREE by not revealing information from later pages in the novel.
Page numbers refer to editions with 385 pages, where the story begins on page 3. Not sure if there are other editions with variant pagination. Please let us know otherwise.
"The Wayvone estate..."
The description sets Wayvone's digs in Woodside or Atherton -- pricey suburbs down the peninsula from San Francisco.
"Gelsomina, the baby"
Also the childlike heroine of director Federico Fellini's La Strada .
Italian for 21st.
Italian: pointed head.
Brunello di Montalcino
Brunello di Montalcino is a red Italian wine produced in the vineyards surrounding the town of Montalcino located about 120 km south of Florence in the Tuscany wine region... In 1980, Brunello di Montalcino was awarded the first Denominazione di Origine Controllata e Garantita (DOCG) designation and today is one of Italy's best-known and most expensive wines. WIKI
Spanish: high places.
Could easily see a "community" being named this in the Bay Area, esp. perhaps around the Los Altos Hills area?
"Mr. Wayvone's compliments"
Two-Ton's deadpan delivery, and instructions to the band, constitute perfect movie-Mafia schtick.
"C'e la Luna"
Youtube has a version by Louis Prima where he sings in both English and Italian, along with lyrics in the description.
"Italian Wedding Fake Book by Deleuze & Guattari"
If this book isn't real, it oughtta be. Fake books are collections of songs that provide basic chord changes for working musicians who need to play said tunes in a hurry like on a gig. The auteurial attribution is a very sly academic joke. Gilles Deleuze (1925-1995) and Felix Guattari (1930-1992) were post-modernist philosophers best known for two esoteric volumes on capitalism and schizophrenia, originally written in French. Volume one was Anti-Oedipus; volume two was A Thousand Plateaus.
"Suddenly she saw another reflection, one that might've been there for a while"
We'll soon learn about DL's prowess at the ninja arts, including the one of not being seen unless she wants to be.
"...wearing a green party dress...athletic, even warriorlike..."
DL is described very much like Artemis/Diana, the Greek/Roman goddess and virgin huntress whose color is green.
"Down in the streets of Honolu-lu ..."
Although Pynchon correctly summarizes the images in the Hawaii Five-O opening sequence and implies that DL's scanner plays the opening theme, the lyrics are a Pynchonian invention. The theme is instrumental. Watch the Hawaii Five-O opening on YouTube.
"Darryl Louise Chastain"
Even DL's last name, Chastain, is suggestive of chastity (as you'd expect in a virgin huntress), but "stained," imperfect. She's a flawed avatar, a preterite goddess.
"Dumbo with that feather..."
The reference is to Disney's animated cartoon feature, Dumbo . The feather was a security symbol that gave the little elephant the confidence to fly when he clutched it in his trunk. (It is rumored that Dumbo is one of Pynchon's favorite movies. Dumbo also appears in Gravity's Rainbow.)
Gates of Frenzy? Cf page 27
"whatever story DL told...could never be the story she knew."
The first ominous hint of the events in Trasero County.
"But DL only smiled back..."
That is, DL doesn't tell Prairie that she's too young to be so paranoid. In other words, paranoia is the correct response.
gowns from the upper reaches of Magnin's
The Joseph Magnin Company was a high-end specialty department store founded in San Francisco, California by Joseph Magnin. WIKI
"Shondra and the kids look wonderful"
The first (easy to miss) inkling of a connection between DL and Ralph Sr.
"You think I'm one of those kids on Phil Donahue..."
That is, The Phil Donahue Show. Prairie (like most of America) is quick to define herself via a TV show.
Just a girlie, with-a-gun...
DL's song brings to mind the famous photo of Patty Hearst.
Good noir word with an interesting history, its meaning in the 20th century shifting from a male, especially young, homosexual, to a gunman.
More Pynchonian mysterioso. And it's a black Trans-Am! A b-a-a-d car, and the perfect ride for a would-be ninja.
Also brings to mind the most popular, computerized, modified Trans-Am on the Tube in the 80's: KITT, from Night Rider. 
They depart "to the stately Neo-glasspack wind chorale, combustion shaped to music, varying as she shifted gears... blending finally into the ground hum of freeway traffic far below."
Pure poetry, and also an exemplary use of punctuation. Go, Pynchon, go! Glasspacks are the most popular straight-through hot-rod muffler replacements ever made. The fiberglass packing provides a slight muffling effect, but does not impede the all-important exhaust speed of combusted products. Sounds great, too.