- Please keep these annotations SPOILER-FREE by not revealing information from later pages in the novel.
The Crying of Lot 49, Chapter 1
a Mexican city on Mexico's Pacific coast. Pynchon lived in Mexico during parts of the 1960s.
Pynchon's alma mater.
(1836 – 1892) was an American financier, who became a leading American railroad builder and speculator. In his lifetime and for a century after, Gould had a firm reputation as the most unethical of the 19th century American businessmen known as robber barons. Wikipedia
Warpe, Wistfull, Kubitschek and McMingus
As Pynchon is a lifelong Jazz fan, the final name could be a nod to jazz legend Charles Mingus.
Fictional California town.
Settecento is the Italian word for seven hundred, and is the standard Italian term for the 18th century (not the 17th century, but the years beginning with 17). In English, it refers to styles of that period.
Vivaldi Kazoo Concerto
Kazoos appear in Gravity's Rainbow.
The name sounds suspiciously similar to Zoyd Wheeler, the protagonist of Vineland.
"Mucho más" is common Spanish phrase, meaning "much more."
Pachucos were Mexican American youth who developed their own subculture during the 1930s and 1940s in the Southwestern United States. They wore distinctive clothes (such as Zoot Suits) and spoke their own dialect (Caló). Wikipedia Zoot suits appear a few times in Gravity's Rainbow.
chingas and maricones
Spanish slang for "fuck" and "faggot".
One identity adopted by The Shadow, a character of pulp fiction, radio shows, and comic books. Cranston was a wealthy young man about town. Wikipedia
Commissioner Weston... Professor Quackenbush
LSD-25, mescaline, psilocybin These hallucinogenic drugs are also mentioned in Gravity's Rainbow. It remains an open question as to whether and to what extent Pynchon took or was influenced by them. 
The Rorschach inkblot test (Pronounced roar-shock) is a method of psychological evaluation. Psychologists use this test to try to examine the personality characteristics and emotional functioning of their patients. Wikipedia
a face is symmetrical like a Rorschach blot
In the graphic novel, Watchmen, written by Alan Moore, there is a character named Rorschach who wears a mask with a Rorscach blot on the front. Moore is a self-professed Pynchon fan: he referenced V. in V for Vendetta and has mentioned Gravity's Rainbow in interview. It is possible, not to say probable, that Moore was inspired by this line.
The TAT is popularly known as the picture interpretation technique because it uses a standard series of 31 provocative yet ambiguous pictures about which the subject must tell a story. It was developed by American psychologists in the 1930s. Wikipedia
Dr. Fu Manchu is a fictional character, an evil genius of Chinese origin, first featured in a series of novels by Birmingham author Sax Rohmer during the first half of the 20th century. Wikipedia
Perry Mason is a fictional defense attorney who originally appeared in detective fiction by Erle Stanley Gardner. Mason was portrayed by Raymond Burr in a television series which ran on CBS from 1957 to 1966. The typical plot involves Perry Mason unmasking the actual murderer in a final dramatic courtroom showdown. Wikipedia
The Profession v. Perry Mason
Roseman may be trying to undermine Perry Mason by arguing that the dramatic courtroom twists in the TV show are actually uncommon in the American legal system.
Bornando el Manto Terrestre
Remedios Varo (1908 - 1963) was a surrealist painter. Wikipedia