Typographical anomalies.

In my Fate of the Artist I sarcastically refer to deliberate irregularities of any sort in the physical text of the book, from a serif in the middle of a paragraph of sans say, to a whole illustration, as 'typographical anomalies'.

Umberto Eco employs as many as 221 images in his The Mysterious Flame of Queen Loana: 'an illustrated novel' (2005). At first it's all reproductions of covers and illustrations from pulp magazines, comic books and sheet music, and at the end, montages and adaptations that he made himself from the same kind of materials.
From the Village Voice article/interview
"Overwhelmed by faces and names, he (the protagonist, Yambo) escapes to his boyhood home in the Italian Piedmont, where he confronts a different inundation—the novellas and comic books from his adolescence. The second section has Yambo delving into this kitsch pool of superheroes, damsels in distress, and cartoonish fascists—relics of Italy's Mussolini generation.

'Obviously, when you write a novel about memory, you have the ghost of Proust blackmailing you,' says Eco. 'But this isn't the case here. Proust goes inside himself to retrieve personal memories, while my character has no personal memories, or madeleines, and is dealing with collective, mineral memorabilia. He's working with external material, not internal material.' Eco has reproduced much of this "mineral memory" in the form of illustrations—period book covers, movie posters, and propaganda material. "The graphics don't illustrate what I've already verbally described," he explains. "They have the function of an 'etcetera,' to give the impression of the abundance of material that I found in my attic."
Eco says he structured Mysterious Flame to mimic the free-associative behavior of electronic navigation."

Eco calls his anomalies 'etcetera'. Another term is loosely coined in the following interview with Jonathan Safran Foer, who has some sixty pages of photos and other novelties (not counting actual manipulations of type and blank pages) interpolated into his Extremely Loud and Incredibly Close (2005), including fifteen pages of flip-book at the end:
"RB:"The graphic tschotskes that are in this book...
...JSF: I am from a generation that was raised with the Internet... It makes a huge difference. And I was raised with a different kind of television and music. Music for example that depends very much on borrowing from different traditions, sampling pieces of other music and overlaying different rhythms and melodies and I think that is reflected in my writing. It was not intentional and it was not an attempt to reflect something about the culture in which I grew up, but it's what I know. And I think that comes across in the typography and in the style in the combination of voices. The world is more of a collage everyday."

I'm sure we're all talking about the same thing.