So very much foreshadowing, and so many Chekhov's Guns, there really needed to be a page to keep track of it all.
- The Transcendent Pig is first referenced So You Want To Be A Wizard, but doesn't show up until The Wizard's Dilemma.
- Irina Mladen, too, is first mentioned in So You Want To Be A Wizard, and doesn't appear until A Wizard of Mars.
- In the New Millenium Edition of So You Want To Be A Wizard, Mamvish, too, is namedropped, and like Irina, doesn't appear until book nine.
- The Moebius spell Nita uses in So You Want To Be A Wizard becomes part of the plot in Deep Wizardry.
- Everything Peach says is foreshadowing for something later, occasionally more than once.
- Fear death by water! Cue Deep Wizardry and the Song of the Twelve... and again at the climax of A Wizard of Mars.
- In High Wizardry, a Demisev and the Stationmaster both show up.
- Pretty much everything Ponch does in A Wizard Alone is foreshadowing for the end of Wizards At War.
- At the end of A Wizard Alone, Carmela's new curling iron arrives.
- Near the beginning of Wizard's Holiday, Urruah tells Nita and Kit not to "destroy [their] host civilization or anything". Uh, yeah, about that...
- Starting several books before A Wizard of Mars, people repeatedly reference "the Martian thing" when talking to/about Kit.
- Back in Deep Wizardry, it's mentioned that "there is no higher price than lifeprice... well, one."
- Probably "losing one's wizardry", which may have fired in book five with the possible consequences of Nita's deal.
- In Wizards at War, there's special focus on Dairine's emerald necklace, but what exactly it says is never revealed. Thanks to Diane Duane's tumblr, we have confirmation that we will learn eventually.
- Darryl is revealed to be an abdal in book five. If he ever finds out, he'll both stop being one and die.
- Pretty much everything Nita notices ever ends up being foreshadowing. So in A Wizard of Mars, when she's looking over Roshaun's family in her Manual, the names/statuses she notices are probably going to come into play eventually...
- On her tumblr, Diane Duane referenced a scene in the as-yet-untitled book 11 involving something bad happening to the Lone Power that is apparently "worse than a silly hat."