Mad Hatter: In the gardens of memory, in the palace of dreams, that is where you and I will meet.
Alice Kingsleigh: But a dream isn't reality.
Mad Hatter: Who's to say which is which?
Alice Kingsleigh: Time is a he?
White Queen: He is not someone you want as your enemy.
Alice Kingsleigh: Please, sir. The Hatter is in danger.
Time: Young lady, your time is up.
Mad Hatter: This cannot be good.
Red Queen: Hello, Alice.
Mad Hatter: Aaahhh!
White Queen: Hatter's counting on you.
Cheshire Cat: We all are.
Red Queen: Oh, Alice, you always were an irksome, slurvish, interrupting thing! Hahahahaha!
Time: Everyone parts with everything eventually, my dear.
Alice Kingsleigh: What's the matter?
White Rabbit: The Hatter's the matter.
Alice Kingsleigh: Hatter is my truest friend. If he's in need, I will help him.
Cheshire Cat: When the day becomes the night and the sky becomes the sea, When the clock strikes heavy and there's no time for tea. And in our darkest hour, before my final rhyme, she will come back home to Wonderland and turn back the hands of time.
Blue Caterpillar: You've been gone too long, Alice. There are matters which might benefit from your attention. Friends cannot be neglected. Hurry.
Time: He is me and I am he.
Time: All of that was or ever shall be.
Answer: The way I interpreted the scene is that Mirana subconsciously altered her own memory to convince herself that she had not eaten the tart to avoid the guilt of the resulting accident. This is a real phenomenon, so it's perfectly plausible. If my assumption is correct, this scene shows Mirana realizing for the first time that she is in fact responsible for everything that has happened since due to a single lie she told.
Phixius