Caesar breaks into the A/V (Audio/Video) Room and steals books. Maybe this is some kind of reference to the fact that they didn't have audio or video recording in Caesar's age, so they had to use books. Of course, they didn't even have the means to mass-produce books until the Gutenberg press, so each book back then would have been custom-made. Still , books didnt exist in Caesars time .
George Washington Carver says, "they perpetuate racial stereotypes" of Gandhi's proposed movie genre. While he says this, he throws a crumped-up mass of paper at a garbage can and misses. Several other crumpled-up missed shots are also shown next to the garbage can. If this were truer to racial stereotypes, Carver would be better at throwing basketball shots. I think the real reason that basketball is popular with black folks is that it doesn't require much of a financial investment in equipment to play the game, unlike, hockey.
Cleo is shooting an epic movie about herself called "The Best Of The Best Of The Best Of The Best Of The Best". Epics are another genre of movies, and one could even say that movies about Cleopatra are another genre, considering that the IMDB lists 43 theatre movies and 11 TV movies on the subject. The most famous one is probably Cleopatra (1963) starring Elizabeth Taylor as the titular character.
Andy Warhol, Mother Teresa, & Teen-Slasher Sex Romps
Abe says, "Film at Clone High used to be just you and Andy Worhol And your disturbing art films. But now, Cleo's doing her epic, Gandhi's doing his cop movie, and Mother Teresa's got that teen-slasher sex romp." Andy Worhol (1928-1987) was a famous pop-artist. He died rather ungloriously from complications following a gall-bladder surgery. Mother Teresa (1910-1997) was a famous nun and humanitarian. Teen-slasher sex romps are a genre of movies, and the season finale of Clone High has "The Sex Romp" as a subtitle. It looks like Mother Teresa's clone is rebelling against her clone-parent like the other clones. Also, the original Mother Teresa must have been cloned while she was still alive.
Thomas Edison operates the coal-powered film projector in the bomb-proof projection room. Thomas Alva Edison (1847-1931) was the original abuser of the patent system, stole all of his engineer's ideas, and took all of the credit. Apparently, Edison's clone has a secret crush on Joan; this is why he gives her such a hard time at the projection booth.
Math & Science
The scrolling background behind Carver during the "Meet Leon Black" movie scene contains elements from various different branches of math & science. It seems to have a lot of partial derivatives from Calculus with Algebra, except that most of the "die" characters look like "a"s and I'm not sure if the formulas make any sense. There is also Chemestry, though I don't recognize any of the molecules other than dihyrdogen monoxide. The big hyrdo-carbon appears to be "C9,H12,O7", though I can't find any reference for this or C10 or C11 (there is a weird symbol in front of one of the C's). I was hoping it might be something interesting like caffeine, LSD, or cocaine. Physics is represented by the famous "E=mc^2" for mass-energy equivalence. And Arithmetic is misrepresented by the dodgy equations "10 - 4 = 2" and "1 + 1 = 3". The first equation would be true in a base-six numbering system, but no such luck for the second.
Adolf Hitler's clone is shown in the audience at the end of Abe's movie. Adolf Hitler (1889-1945) was the totalitarian dictator of Nazi Germany who brought us WWII. I'm not sure if his clone appears again in the series. Fan Sol Klein points out that like most of the other clones in the series, this clone may be a little different from his clone-father since he is wearing a yellow peace sign instead of a swastika.
Sigmund Freud, Fold-Up Chairs
Joan smacks Sigmund Freud in the face with a fold-up chair after he figures out her movie. Sigmund Freud (1856-1939) was a psychologist who developed psychoanalysis and was overly interested in and thought that everything could be explained by repressed memories, dreams, and sexuality. No wonder he understood Joan's film.