Wonder how come Hank the Mule wasn't able to talk until he reached Oz. It's been indicated that in any of the lands surrounding Oz animals can talk. Billina the Yellow Hen was able to talk in the land of Ev in Ozma of Oz. Jim the Cab horse could talk in the Vegatable Kingdom in Dorothy and the Wizard in Oz. Yet in the Rose Kingdom, Hank can't talk.

Another oddity is that the Shaggy Man didn't recognize Polychrome, even though they met each other in The Road to Oz.

Another oddity is that Glinda's palace is apparently located in the North, when she is the Good Witch of the South (and to make matters worse, the 1939 movie also had Glinda coming from the North). Is Glinda 'holding the fort' for the vanished Good Witch of the North (whom Baum seems to have forgotten about at this point)?

In "The Emerald City of Oz," when Ozma and her friends are watching the Nome King and his allies preparing to enter the tunnel in the Magic Picture, Ozma points out that they can hear what the people in the Picture are saying, and she and her friends hear the Nome King's whole conversation with his allies. Yet in this book when the Shaggy Man and his friends are shown in the Picture he needs to use a handheld device to communicate with Ozma. Perhaps the ability of Ozma and her friends to hear the Nome King and his allies in "Emerald City" was the result of Ozma casting a spell, since in other books it is implied that the Picture is generally silent--for example, in "The Tin Woodman of Oz" Dorothy and Ozma don't know until they meet up with the enchanted Tin Man and his friends that the Canary is actually Polychrome, which they would surely have known had they heard the travelers' conversations as they watched them in the Picture. (And at the end of Ruth Plumly Thompson's "The Royal Book of Oz," the Wizard uses a magical instrument and magic word to make audible the events on Silver Island shown in the Picture.)