During the course of the Oz comic series, there were several spinoff titles. The only one that was printed under Caliber Comics was Oz: Daemonstorm which was part of a company-wide crossover event with several unrelated titles. It takes place just before the end of the original Oz comic where Jinjur, Lion, and Scraps team up with two dimensional-hopping cyberpunks to free Jack Pumpkinhead from an evil daemon. This particular one-shot is slightly unnecessary because it doesn't really add to the ongoing Oz storyline at, but worth getting if you wanted to see Scraps get some more screentime. The next one is the Wogglebug Special which is a tie-in to Dark Oz and was actually written by artist Bill Bryan. It basically shows what happened to the Gilikens during the Goblin invasion, and how Wogglebug buys it.
After this is one of two seperate issues of Arrow Anthology which was Arrow Comics' showcase of other titles and featured stand-alone short stories. In issue #2, we learn what happened to Dorothy after falling into Glinda's magic mirror and ends up in Wonderland, which leads into the 3-issue mini-series of the same name, featuring art by Danny Wall and Bert Reinke. In a plot which seems similar to Tim Burton's Alice In Wonderland, a secret resistance is planning on overthrowing the Queen of Hearts who has apparently recently gone evil. Alice here is a teenage English girl who has been trapped in Wonderland for years, and is the acting leader of the resistance. The Queen in turn had been using the White Rabbit to cross dimensions and either steal magic items from Oz, or trade them with Mombi. The Cheshire Cat turns up to tell the rebels that the White Rabbit has been betrayed. "Chet" lets everyone know about how he was working part-time with Rabbit for the Queen, and how she used one of Mombi's magic necklaces to subdue him. It is revealed that the Queen has been gorging down on the essences of her subjects' severed heads, and has mutated into a giant Jabba the Hutt-lookalike. Alice, Dorothy, and the other rebels launch an assault on the Heart castle, but their member Joker turned out to be a double-agent for the other side, and gets them all captured. Mad Hatter and Chet take out Joker, and free the others. They then proceed to take on the Queen's forces, and discover that she has had Tattypoo(the Good Witch of the North)as her prisioner this whole time. Tattypoo releases the Queen from her head-devouring curse which turns her back to normal, and she goes back to Oz with Dorothy, which is right at the end of Dark Oz where the timeline is being rewritten.
Following this is issue #4 of Arrow Anthology that has a prelude to The Land Of Oz. It starts out with Ozma reading the Book of Beginnings which is supposedly the counterpart to the Book of Undo shown at the end of Dark Oz. It flashes to Earth where pilot Travis, his fiance Cat, and her bookworm younger brother Sean are on a flight in Travis' plane which goes through a tornado that takes them just outside of Ev. After crash landing, they are surrounded by some ticked-off Wheelers. This leads into issue #1 of the regular The Land Of Oz comic.
I'd say that most of the spinoffs were okay in regards to the other three main series, although the stories from Arrow Anthology might have been better off included in the pages of the actual series they acted as prequals to. The Wogglebug and Daemonstorm one-shots are mainly for completionists. Wonderland on its own is a decent comic, and is yet another chance for to have Dorothy and Alice meet up in an outside story, although it might have been nicer if it Wonderland had established itself as its own series instead of it being connected to Oz first. I'm unaware of if and how these spinoffs might be included into Transfuzion's Oz trade paperbacks, but hopefully they'll be released in chronological order with each series to keep the stories straight.