This is an issue that I noticed at the end of the first preview stream, and it's simply a little annoyance. AI driven dirt trains have the headlights set to "Bright Aux" on both the front and the rear locomotives. I'm pretty sure that realistically, the locomotive at the back of the train would have the headlights set to "Dim". Here's me doing a bit of railfanning at the lovely and totally bright hour of 5 AM. Front of the train (it's correct): Rear of the train (shouldn't have ditch lights on, should probably be set to Dim):
I'm not 100% sure about this, but AFAIK the loco on the back only has the lights on if it can move in that direction (as in when the train is shunting or moving back and forth in a yard for whatever reason).