You can find this in the TUNNEL of the Washington D.C. Metro, from Metro Center to Chinatown on the red line - look out your left. My friend said she spotted another kind of trailer somewhere else but this is the only one of Coraline that we saw. Plz comment if you know how this works - we think it's a series of images projected onto a wall, like video frames, and the image looks like it's moving because the train is passing by so fast. But this is a theory.