Ned Brown and Al Badham were completely fictitious characters with no real-life equivalent. A tall tale exists that L. Frank Baum was challenged to a duel over mention of a bride's "roughish" smile in The Aberdeen Saturday Pioneer (called the Dakota Pioneer in the film). In tellings previous to the film, both men ran from the duel at the sound of apparent gunshots. A version of this story first appears in print in Baum's 1912 novel, Aunt Jane's Niece's on Vacation, and was recounted for The Baum Bugle in a series of biographical articles by Harry Neal Baum. Nancy Tystad Koupal's research into the Pioneer (see the introduction to Our Landlady) shows that the only instance of "roughish" was in a story in which Baum recounted having unwittingly walked in on a community theatre rehearsal, and the smile of an actress. The film's depiction of "big" presented as "pig" was fictitious. The identity of the duelist, if the story is true, has never been identified, so the filmmakers had to invent a character, whom they named Al Badham, simply to present the anecdote. There is no indication that this story actually inspired the Cowardly Lion.
Some L. Frank Baum biographies say that book publishers in 1900 refused to accept any title which had a jewel's name in it, ergo he had to changed the title from The Emerald City to The Wonderful Wizard of Oz. In 1910, his newest Oz series installment was entitled The Emerald City of Oz. Either publishing customs had changed in the intervening decade, or Baum's clout as a best seller overrode any lingering worries.
John Ritter (L. Frank Baum) and Jason Ritter (Harry Neal Baum) are father and son in real-life. Nancy Morgan (Helen Gage) was John's wife at the time and Jason's mother.
The antagonism between Frank and his mother-in-law is largely fictitious. It is unlikely that L. Frank Baum based the Wicked Witch on Matilda Gage. In fact, Mrs. Gage wrote history treatises alleging that "witchcraft" was a stigma which the medieval Christian Church used to defame female folk healers from obscure European cultures. Baum appears to have been inspired by these treatises in his depiction of witchcraft. In most of Baum's fantasies, witchcraft is a science which is used mostly for benevolent purposes, but is more prominently misused by the various Wicked Witches.
Jon Ritter was actually distantly related to L. Frank Baum on many lines. The closest related they were was 13th cousin twice removed.