It happened in an interview with a writer for Examiner.com
You reprise your role as the White Witch in “The Chronicles of Narnia: The Voyage of the Dawn Treader,” the third film in the “Narnia” movie series. How long did it take you to film what you do in that movie?
Oh, you know I’m in it? Yes, it’s true.
I know you can’t give away any spoilers, but it’s not a secret that you’re in the movie since you’re shown in the movie’s trailer.
Well, I’m amazed that that they would put [my scene] in the trailer, because I spent less time filming it than I spent speaking to you [in this interview]. [NOTE: This interview was 23 minutes long.]
Okay, for those of you who have never been on a film set: 23 minutes of filming doesn’t really amount to a lot. Granted, it was likely a rough estimate, but when they’re filming something like this they usually do many takes of the same shot. Not just from different angles, but to get different performances each time. This shows something that should ease your mind: she’s not in it very much.