Plot hole: The White Knight is knocked out by a bomb in his attack on the casino. When he regains consciousness, he fires one last crossbow shot, which he thinks destroys the casino. But who loaded and cocked the bow for that last shot? Crossbows don't reload themselves.
Continuity mistake: Before Hatter leans towards Alice for a kiss, his hands were by his side. But in the next shot, his hands are already on her waist.
Continuity mistake: In the final showdown between the Queen and Alice, in the wide shot, you initially see the Ten of Clubs standing beside the Queen, but when it moves to close-up, he has disappeared from her side, only to run into the scene behind Jack and Duchess moments later. (02:52:45)