Big-Lipped Alligator Moment: The scene where Alice sees her dead cat Dinah, follows her through a door and into her father's old study where Dinah grins and disappears. She never tells anyone about it and it has nothing to do with the rest of the story.
It does foreshadow the fact that Alice's father is in Wonderland, though it's more for the audience's benefit than any of the characters'.
Most of the scene where Alice is trapped in the copy of her house by the Tweedles would count. This includes a part where she turns into a younger version of herself and fearfully walks into a room to find a pig in a bonnet in a crib. Of course, the people who made the series used this all as an opportunity to shove a ton of references to the book in.
Fanon: The technicians who work under Carpenter and Walrus are normally referred to as Eggmen.
And Lady Gaga is secretly from this version of Wonderland.
Considering these are the same guys who whipped up Tin Man, the fandoms share a lot of writers and discussion boards.
There's also a lot of crossover with Primeval thanks to sharing a cast member.
Genius Bonus: The White Knight, when meeting Alice and Hatter for the first time, says, "My nana used to say that if I was the only eligible bachelor left in the world, there wasn't a warthog or wall flower who'd polish my escutcheon." An escutcheon is a type of shield, but it is also used in medicine to refer to something else.
Memetic Mutation / Iconic Outfit: Oh, so many. The playing card suit worn by those attached to the Casino indicates their function in Wonderland:
Diamonds: Dealers, dancers, scientists, technicians and anyone else dealing directly with Oysters.
Clubs: Bureaucrats and pages.
Spades: Security force; the strongest members are referred to as "Aces" despite being all Spades of various high-end numbers.
You'd think Mad March's new head would be something of a Nightmare Retardant...but it's not.
No, it's the scariest thing about him.
What about the sight of two children being kidnapped and taken to be drugged and held captive in the clubs? Or the thought that it could happen to anyone for that matter?
There's plenty of fuel for the acro- or aqua phobic in the audience.
One-Scene Wonder: Tim Curry as Dodo is only in one scene less than five minutes, but highly memorable since he's Tim Curry.
Ugly Cute: The Jabberwock, which looks like something out of Spore.
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