This was--God help us--a real toy. You can see Melanie, her mall, her friends, and even her escalator here, which even includes the tag line, "It's cool at the mall."
Also, here's a guide to all the Melanie's Mall products.
Pynchon commands at least the very basics of Dragonball Z's plot, as evidence by the grouping of Goku with his son Gohan within a comma, plus the title of "Prince" Vegeta. Someone who knew absolutely jack about the show would have written, "including Vegeta, Goku, Gohan, Zarbon, and others."
Use the Source, Luke
"Multi-User Dungeon" games, an old-school, text-based video game. Wikipedia
Virtual Reality Modeling Language, pronounced vermal or by its initials, originally—before 1995—known as the Virtual Reality Markup Language.
Jolt Cola is a carbonated soft drink produced by Wet Planet Beverages. It was created in 1985 by C. J. Rapp as a highly caffeinated cola and was targeted towards students and young professionals, stressing its use as a stimulant in a similar manner as energy drinks. From WIKI.
Fernet-Brancas with ginger-ale chasers
Fernet-Branca is a spirit from Italy that's extremely popular in the San Francisco Bay Area, in fact, the area accounts for 25% of its consumption. Likewise, it's most commonly served in the area with a "ginger back."
celestial pastry exercise
pie in the sky.
A Ponzi scheme is a fraudulent investment operation that pays returns to its investors from their own money or the money paid by subsequent investors, rather than from profit earned by the individual or organization running the operation. The Ponzi scheme usually entices new investors by offering higher returns than other investments, in the form of short-term returns that are either abnormally high or unusually consistent. Perpetuation of the high returns requires an ever-increasing flow of money from new investors to keep the scheme going. The scheme is named after Charles Ponzi, who became notorious for using the technique in 1920. While Ponzi didn't invent the scheme (for example, Charles Dickens' 1844 novel Martin Chuzzlewit and 1857 novel Little Dorrit each described such a scheme), his operation took in so much money that it was the first to become known throughout the United States. Ponzi's original scheme was based on the arbitrage of international reply coupons for postage stamps; however, he soon diverted investors' money to make payments to earlier investors and himself. From WIKI.
names of horror film villains: Jason Voorhees of Friday the 13th and Freddy Krueger of Nightmare on Elm Street.
Courtney Pulitzer's downtown soirees
Courtney Pulitzer branched off from her @The Scene column with @NY and created Courtney Pulitzer's Cyber Scene and her popular networking events Cocktails with Courtney. From WIKI.
Kalimotxo, also known as cocavino, is a drink consisting of equal parts red wine and cola-based soft drink.
Programming Perl, best known as the Camel Book among programmers, is a book about writing programs using the Perl programming language, revised as several editions (1991-2012) to reflect major language changes since Perl version 4. From WIKI.
A trademarked film presentation process that uses three separate but locked together cameras, three synchronized projectors, and a large deeply curved screen. Wiki YouTube Kind of interesting, especially when considered as an early type of virtual reality.
An animated color effect, smoothly transitioning: "flaring beyond the basic videogame brown of the time into the full color spectrum of very early morning." Think "crossfade" (which Pynchon uses on the next page) and "dawning" so that the transition to color is from the bottom to top, like dawn. This isn't a standard Web-design term.
up and down stairways, through dark pedestrian tunnels, emerging into soaring meta-Victorian glass- and iron-modulated light, through turnstiles whose guardians morph as she approaches...
Is it just me, or does this scene here bring to mind the knotting into opening of Gravity's Rainbow?
When she looks out the rear window of the vehicle, instead of seeing detail and color like she sees looking forward in "the other brighter world", the details aren't rendered looking back, instead fading to Netscape gray which is the background color the Netscape browser rendered if no specific color was coded in. Looks like this...
As for "entropic dwindling" ... entropy is the gradual decline into disorder which happens with all closed systems. Pynchon's use here is slightly metaphorical, referring to the lack of energy put into the events dwindling into the past. Pynchon frequently uses entropy as a metaphor. 
I BELIEVE YOU HAVE MY STAPLER
"I Believe You Have My Stapler" is a catchphrase originally uttered by the character Milton Waddams in the 1999 movie Office Space. The movie is about a group of employees who hate their jobs and decide to rebel against their greedy boss.
A Markov chain, named after Andrey Markov, is a mathematical system that undergoes transitions from one state to another, among a finite or countable number of possible states. It is a random process usually characterized as memoryless: the next state depends only on the current state and not on the sequence of events that preceded it. This specific kind of "memorylessness" is called the Markov property. Markov chains have many applications as statistical models of real-world processes. From WIKI.
...bleeding-edge technology...No proven use, high risk, something only early-adoption addicts feel comfortable with.
Perhaps a gratuitous annotation, but it seemed appropriate to highlight how Pynchon uses the title of the book in the book itself.