Yes, that's right. At one camera angle, I watched the stars move down the sky to sink behind the distant skyline (2:31 & 4:06). At another camera angle, they seemed to turn in an arc (cartwheel) in the sky (see just before 2:07). It makes it very obvious where the axis is, upon which, the sim world spins.
You have a good eye. As you have indeed figured this out good, the 'axis' is somewhere at the rich part of the town, where the celebrities are living. You normally won't even notice that, because even at speed 3 nothing seems to be noticed that leads to that, and that is how EA did wanted it.
The world is not moving, although I understand you are thinking that. In fact, you can see Bridgeport (and every other town) as being a flat terein in the middle of a spherical object. The inside of that object has a video on it protected with the daylight sky on the top and the night at the bottom. As this spherical object is moving with a random town in it, the sky will 'turn around' into night and vica versa in a endless loop.
In basics consepts, the whole FOX logo thing that I have modefied has been made in the same way: an object (FOX) with a background sphere which makes it look like you are surounded in a 3 dimensional world.
As for the light sources I was taking about before, they must have been placed around different fixed points in the sky. You won't notice them becasue they obviously are made as being ' empty'. Because the sphere sky is moving around, those light sources are moving also.
Because the sun is not a light source (otherwise you would seen it shying through the buildings which will cost you a tremandiously amount of processor power) there is no time at night where it is totally dark.
In real life, at night the moon is reflecting the sun, but ingame this is not possible if the light sources are on differnt points in the sky.
