Johnny Depp, who says that he likes "an obstacle" while filming, admitted that he found the process of filming in front of a greenscreen "exhausting", and that he felt "befuddled by the end of the day".
Alan Rickman was originally going to have his face composited onto the animated Caterpillar Absolem. He was filmed recording his voice in the studio, but the idea was eventually scrapped. The animators did, however, try to give Absolem's face characteristics similar to Rickman's.
Before Tim Burton was involved with the project, Anne Hathaway was offered the title role of Alice, but she turned it down because it was too similar to other roles she had previously played. However, she was keen to work with Burton, so was pleased to be cast as the White Queen. She shot all of her scenes in two weeks.
The Mad Hatter asks Alice several times, "Why is a raven like a writing desk?" This is directly from Lewis Carroll's "Alice's Adventures in Wonderland". Carroll admitted that there never was an answer to the question. He made it up without an answer. He did provide one possible answer years later after many requests from his fans for the answer: "Because it can produce a few notes, tho they are very flat; and it is nevar put with the wrong end in front." ("Nevar" = "Raven" spelled backwards. Carroll's deliberate misspelling is often erroneously "corrected", obscuring the point of the joke.) Another answer, from the American puzzler Sam Loyd: "Because Edgar Allan Poe wrote on both." Over the years, numerous others have come up with possible answers as well.
Tim Burton and Johnny Depp worked hard to give the Mad Hatter more depth and presence than in past portrayals. In fact, the pair swapped sketches and themes for the character prior to creating this new version.
Tim Burton: [distorted female face] The Red Queen has a ridiculously shaped face, and her hangers-on wear absurd disguises to conform to her expectations.
Tim Burton: [Stanley Kubrick] Tweedledee and Tweedledum resemble the Grady "twins" from O Iluminado (1980).
Tim Burton: [O Mágico de Oz (1939)] Some people Alice knows in England have parallels in Underland, although they are not played by the same actors as in Oz.