Firefly Easter Egg - A Nod to Lucas

In episode 3 during the train robbery, pause at 24:08 when the camera is looking at the train from above, inside serenity. You can clearly see the train has A1138 written on it, which is a reference George Lucas made in the Star Wars movies, as well as many fans of Lucas in their own shows and movies. You can also see the number written smaller on the hatch they enter the train through.