Note - this particular cartoon has alot of hidden stuff in the background - enough that I've devoted a whole page to it! The books in the backgrounds are full of silly titles and references to people at the studio.

Browsing the shelves

Lotsa Books   As you scan this shelf full of books there are a few things to notice. The leftmost book is by "Pierce" while the next book (titled "IT") is by "Ruth Pierce". The first book could refer to either of the Pierces at the studio: Tedd or Ruth. The 2nd is obviously Ruth's and perhaps they are saying that Ruth had "IT" (a popular expression of the day).
The next book is "The Merchant Price" by "Willie King". Willie was a local merchant who set up a lunch cart on the lot and was a popular spot for drinks and snacks. The next book is by "Dorothy Hill" (who I'm guessing was an inker or painter but haven't confirmed that) while the next one to the right of this is "The Six Hour Day" by "Ray Katz". Ray Katz was one of the bosses at Schlesinger's and his name found it's way into many backgrounds.

[Select to see more]

More Books   Continuing along the shelf, more interesting books appear. "Touchdowns and Fumbles" is by "Binder". That would be Henry Binder - one of Leon Schlesinger's business managers. Next after that is "The Old Master" by "Art Loomer".

Books in the background   Behind Mr. Hyde there is a book entitled "How to Influence Cards and Make Money" by "Binder" and the skeleton is in front of "Little Man What Now?"

Another book...

What now?   Another book toward the right end is called "Hygiene and Sanitation" which was printed by "Lysol Press" (Lysol is a popular household sanitizer).

Cheers!

And the crowd goes wild!   Some of the books have familar names on them: Binder, Tashlin (the director), and Johnnie McGrew (layout artist).

"The Good Earth"

A talking book.   The novel "The Good Earth" has a figure praying. During the prayer he mentions "Papa Leon and Uncle Ray". These would be references to the studio bosses Leon Schlesinger and Ray Katz.

"The Thin Man"

A Memo...   The memo pad on the desk has a note written: "ask the boss for a raise". This was apparently a small act of defiance pointed at their boss at Termite Terrace, Leon Schlesinger, who had a reputation for bring notoriously cheap.

Dogs and Wolfes

Another Interesting Title   Take a look at the red book to the left of the bulldog. "Mexico and Seroritas" by "Wolfe" is another appearent mention of Ralph Wolfe.

Three Cheers!

More books! More Familiar Names!   All the books lying on their sides have something noteworthy. "Jovial Boys" is by Cal Howard - an animator and writer. "Lyric Poems" is by "Dave Mitchell".
Then there's "Guilds - Their Formation and Management" by "Darling in collaboration with Ted Pierce". There are two people who might be the "Darling" here - Keith Darling or Charlotte Darling. Both worked there at the time. And then finally there is a book called "History of Hollywood" by "Loomer". This would be Art Loomer.

More books

Famous Authors   A couple of these books have familar names for the authors. "Sweet Sioux" is by "Freleng" (which is Friz Freleng of course). The next one is "Apache Trail" by "Wolfe". This is another Ralph Wolfe sighting - the second one in this film.

Carl's Book?   We can't see all of it, but there is a book called "??? Hills" by "Stalling". This must be a nod to the musical director Carl Stalling.

Key Books

Key Titles   As you examine some of the books here, yet more interesting names emerge. There's "Keys To Success" by "Kat(z)" - yet another creative use of Ray Katz' name. There is also "Key To The Affections" by "Darling". It's hard to know whether this was supposed to be Keith or Charlotte Darling. And then the is a book we can't quite read all of: "(Ha)ve Laughs At (?)K Smiths" by Dorothy Worth.

Look at the books

Names and more names.   There are several books behind the characters to examine. The leftmost book is called "Memoirs of a Wolf" by Norm Spencer. Next to this is "Tiajuana Wash" by Hardaway, "Ride Em Cowboy" by Bentley, "(??) Harem" by Frank Powers and "(??) By Fives" by Ray Katz.
Norm Spencer was the composer for this cartoon and Hardaway refers to Ben "Bugs" Hardaway, another Warner Bros. director. Bentley was an animator named Robert Bentley while Frank Powers ran the ink and paint group. Ray Katz has appeared so often - well here is yet another!
Continuing to the next image, we find "(??) Arabian" by Ann Almond; "Silky Terrier" by Betty Burke and "??? Nights" by Melvin Millar. Ann Almond was a paint mixer and Betty Burke was an inker. Silky Terrier is a breed of dog - maybe she owned one? Melvin Millar is an animator and writer whose name appeared often in backgrounds.
Incidentally, Ann Almond and Betty Burke appear as authors of books a year later in Sniffles and the Bookworm
[Thanks to Jerry Beck for information about Ann Almond and Betty Burke.]
In the third image most of the books are the same but one additional title is now visible: "(??) the Valley" by Tex Avery. Tex Avery was one of the studio directors.

Wrapping it up

One Final Katz Sighting   Through the smoke we can see one final gag - some words at the bottom of a book which say "Katz Publishing". One final Ray Katz sighting to wrap up this film - that brings the total to a whopping 6 Katzes!