"The Mystery of the Mystery Machine" is the first episode of The Scooby-Doo Detective Agency'. The story is an alternate continuity origin of the Mystery Inc. gang.
- This version of the Mystery Machine combines Scooby-Doo! The Mystery Begins (Daphne Blake owned it) and Scooby-Doo! and the Goblin King (a wizard transforms the van into a Monstrous Machine).
- WNSD episode: "It's Mean, It's Green, It's the Mystery Machine": The area which houses the Mystery Machine's brief sentience is where Fred builds his upgrades.
- SDWAY episode: "What a Night for a Knight": A front page headline foreshadows the events of the case.
- APNSD episode: "A Bicycle Built for Boo!": The Daily Babbler makes a cameo appearance.
- SDWAY movie: Scooby-Doo! The Mystery Begins: The cast reprise their roles for this series.
- SDWAY movie: Scooby-Doo 2: Monsters Unleashed: The old high school clubhouse from the swamp makes its first appearance. Also, the group photo is taken, but with the new actors in place of the old ones.
"Who's mystery machine?"
-Velma and Fred banter about the