If Lewis Carroll is leveling a critique at adulthood in Alice's Adventures in Wonderland, that critique is almost certainly that adult society is fundamentally arbitrary and irrational in its rules, dictates, and expectations. This is why Alice herself is so often confused throughout the book: Wonderland is fundamentally illogical, in such a way that the rules Wonderland seems to run on do not make any sense as far as she understands the world.
A large part of Alice's difficulties in understanding Wonderland is that, to a very real extent, Wonderland itself tends to rely greatly on the manipulation of language. We see this frequently throughout the book, with Carroll's delight in puns and the double-meanings of words: take for example, in chapter 3, with the mouse's boring lecture on William the Conqueror (playing on the double-meaning of the word dry).
At times, this even reaches the level of sophistry, as can be seen in the tea party scene, where the guests confuse Alice, reversing the order of sentences to undermine their meaning. When she suggests there's no fundamental difference between "I say what I mean" and "I mean what I say," they throw out more radical examples: "I see what I eat" becomes "I eat what I see," "I like what I get" becomes "I get what I like," and "I breathe when I sleep" becomes "I sleep when I breathe" (chapter 7). Part of what makes Alice so overwhelmed by this entire experience is that she is generally sincere in her speech and is thrown off balance by the kind of verbal trickery and manipulations that are common in Wonderland.
Wonderland's fundamental irrationality extends beyond the realm of language games, however, to also effect the internal logic that dictates how this dreamworld operates. Remember, this is a world where a baby transforms into a pig and where croquet is played with flamingos being used as mallets and hedgehogs being used as balls. We have the absurdity of the Queen of Hearts sentencing all and sundry to death by beheading, even as the king pardons her would-be victims behind her back. Moreover, note the degree to which this insanity has become normalized: to the residents of Wonderland, these irrationalities go unquestioned. They are all part of the world in which they live. (As the Cheshire Cat puts it in chapter 6, "we're all mad here.")
Applying this vision of Wonderland to adult society suggests that, at its core, the adult world is shaped and dictated by its own arbitrary rules and expectations. When seen through a child's eyes, however, those dictates make little more sense than Wonderland itself.