Among all the odd formating things in Mumbo Jumbo, footnotes would easily be able to be dismissed as unimportant or only focused on as a source of "further information" and "sources". It has been mentioned that Ishmael Reed includes an entire bibliography at the end of Mumbo Jumbo which contains most of the sources referenced by the footnotes. They give the story a quasi-academic quality, obviously interrupted by the dubious nature of the sources and questionable context of the quotes. More than that, footnotes are a tool to make the reader feel as if they are sharing an inside joke or superior knowledge with the narrator/author.
While footnotes tend to be rare outside of scholarly works, they can be found occasionally in other works of fiction. One book which uses them extensively is The Amulet of Samarkand by Jonathon Shroud. The narrator of the book is a demon/jinni who is over four thousand years old. What makes the book especially fascinating are the extremely cynical and sarcastic quips from Bartimaeus, the demon, as well as his lengthy tangents and stories which are stuffed into sometimes multi-page footnotes.
I believe that Mumbo Jumbo and The Amulet demonstrate one quality that a good postmodernist history should have. Footnotes allow there to be a narrative as well as to contain the author's desired skepticism or support of that narrative. As we read through history, especially the sanitized versions, we are constantly bombarded with words which have certain connotations. Footnotes are a way that would be ideal for a postmodernist historian to provide context to people and motivations. It is equally likely that the historian would use it to provide an "alternate" view of history, yet one that is either equally plausible or equally hard to disprove.
