A few things that weren't in the books are in A Series of Unfortunate Events.
- If a sequence near the start of Episode 1 is any indication, the method that is used to start the fire in the Baudelaire mansion is a large magnifying lens, similar to how it was done in the film. A page from The Incomplete History of Secret Organizations implies that the spyglasses can be used as a magnification lens in this way.
- Aunt Josephine admitting that she and the Baudelaire parents made secret codes.
- The VFD logo is Olaf's eye tattoo (in the books, it was assumed to be a regular tattoo in the shape of an eye until around The Carnivorous Carnival).
- Jacquelyn is seen threatening Count Olaf with a harpoon gun on the Prospero (a cruise ship featured in The Unauthorized Autobiography).
- The motif of spyglasses from the film, which did not appear in the books, has been ported over to here.
- At the end of The Wide Window: Part 2, the Baudelaires run off to Lucky Smells Lumbermill to find more information on their parents. In the books, it is merely their next home on Mr. Poe's list. This is even referenced at the start of The Miserable Mill: Part 1, where Mr. Poe, in a panic about the children running off, screams "It's a catastrophe, it's unprecedented, it's—off-book..."
- Dr. Orwell uses her hypnotism skills on the entire Lucky Smells Lumbermill staff instead of just Klaus to prevent them from quitting their job.
- In the books, Dr. Orwell was just a toadie of Olaf's who he promised to split the fortune with; here, she's Olaf's ex and a former member of V.F.D.
- In the fourth book, the Paltryville City Hall Library only had three books. In the series, it has full shelves, but they're all of the same book.
- The series reveals specifically how Dr. Orwell hypnotizes Klaus. The process is similar to the Ludovico technique from A Clockwork Orange: she starts by forcibly strapping him down to a chair (a standard procedure for nervous little boys) and giving him a regular eye exam ("Do you see an E or A on screen? An A or a C?") but then starts saying and showing onscreen strange pictures like "A sea (C) or a lake? A reptile or amphibian? A fire or an accident? A parent or an arsonist? TELL ME WHAT YOU SEE, KLAUS!" and the images start flashing faster and faster, putting Klaus under hypnosis.
- We never did get to hear the end of the sentence that began, "Beatrice, Count Olaf is my—" in the books, although The End did hint at it. But see Wham Shot below...
- The Snicket File. Originally just a regular document in the books, has been upgraded to a small film in the series featuring Jacques Snicket.
- In the books, the fortune teller "Madame Lulu" is simply the alias of a woman named Olivia, an independent party with a good deal of VFD knowledge, likely having been an agent in the past, or else aspiring to become one after learning much about them. The series expanded "Madame Lulu" into twofold by developing the history of the disguise and of Olivia. "Madame Lulu" the guise is changed to be a rotating undercover position held by the operative currently most skilled at gathering information, and Olivia is simply filling in for the current Madame Lulu (Kit Snicket) who is out retrieving the sugar bowl from Heimlich Hospital. Olivia herself also gets an expanded role and a last name (Caliban, which appeared in the books in The End), in a significant case of Developing Doomed Characters—she first appears as an idealistic and kind school librarian in Prufrock Prep in "The Austere Academy", and is recruited by Jacques Snicket into VFD after she stays on the Baudelaire case and catches Jacquelyn's attention. From there, she falls in love with Jacques as she works alongside him, and adopts the Madame Lulu disguise after his death and Kit's absence, whereupon she recognizes the Baudelaires and works with them until meeting the same grisly fate as in the books.
- "The Bad Beginning: Part 2", shortly after the Baudelaire Fire, we see Count Olaf using in his improvised "Yessica Haircut", consulting Mr. Poe to have the Baudelaires delivered to Count Olaf's care.
- The relationship between the Snickets, the Baudelaires, and Olaf is pretty much fully elaborated upon in Part 2 of The Penultimate Peril. Furthermore, unlike the books where the notion only gets expressed in the very last few chapters of the final book, it's much more explicitly shown that Kit and Olaf once had a thing for each other.
- The End reveals quite a bit about V.F.D. and the ultimate fate of the Baudelaires. Ishmael was the founder of V.F.D. and principal of Prufrock Prep before he came to live on the island. The sugar bowl contains sugar made from a special botanical hybrid that immunizes against the Medusoid Mycellium. The Baudelaires spent a year on the island raising Beatrice before returning to the outside world, where they proceeded to have more adventures that were generally more positive.
