Actress Kristen Bell surprised an audience at a Frozen sing-along event in California on Friday (22Aug14), by making an appearance to introduce the film. The Veronica Mars star, who voiced Princess Anna in the animated movie, took to the stage at the El Capitan Theatre in Hollywood, where she was joined by characters dressed s Anna and her sister, Queen Elsa. After the appearance, which landed Bell a standing ovation, she told EW.com that she's still pinching herself in disbelief about the 2013 animation hit's international success. She said, "There is no way to foresee a movie's success or how much it would touch people. You strive to make the best movie possible and I felt like we did that... "It's especially invigorating because music is what brought me to performing and acting in general. From doing so much non-singing work and being satisfied with that, to have it then be able to reincorporate music into what you do as a performer - which is hopefully tell a good story - it feels weirdly full circle. To be able to do it is one thing, to be hired to do it is really lucky." Disney’s Frozen Sing-Along is set to run at El Capitan until 7 September (14).