Q: What are all the different cards in different versions where you get to draw the top card and play it immediately?

A: There are many analogues to Wormhole (the first one we made) or Mystery Play (the most generic themed one). Some may require a token action (click your heels together to use Magic Shoes in Oz Fluxx, for example) or condition (if a certain card is in play) to activate them but they are essentially all the same kind of card.

Mystery Play in Fluxx 5.0 and SE
Wormhole in Star Fluxx
Shiny! in Firefly Fluxx
Allons-y/Geronimo! in Doctor Who Fluxx
Spontaneous Reaction in Chemistry Fluxx
Egads! in Batman Fluxx
Unknown Variable in Math Fluxx
Great Idea! in Stoner Fluxx
Magic Portal in Adventure Time Fluxx
Magic Shoes in Oz Fluxx (if you click your heels together three times)
Open The Door in Monster Fluxx (If the Spooky Door is in play)
Open A Gift! in Holiday Fluxx (if The Gift is in play)
Chemical X in Cartoon Network Fluxx (if at least one Powerpuff Girl is in play)
Time Doorway in Regular Show Fluxx (if the Time Machine is in play)