-No clue if this has been mentioned yet but I don't remember seeing a topic on it.
http://images2.wikia.nocookie.net/__cb20101129225308/fallout/images/archive/e/e1/20101223134802!Fallout_New_Vegas_Map_v0.03.png
look at above link and look at the red box "G6" (its near the bottom). Well its on the railroad tracks and if you follow the main line to the very bottom it goes to a busted bridge (over crescent canyon) which you can't cross. But if you look at the little section right below "G6" that veers off, it is a little section that veers off into a tunnel. Nothing exciting, but the entering pedestrian door is boarded up and inaccessible so you can't go in the tunnel (like you can for most train tunnels in FO3 and NV). And also at the door of the tunnel there is a lottery ticket, which is an odd place for a lottery ticket (even though it is kinda near Nipton). I have always wondered what the significance of this is and eventually thought that it very possible was a place for some Kind of DLC or expansion since it is not currently used and is in the middle of nowhere it easily could be a tunnel through the mountains to get to somewhere out of the Mojave. Anyone else ever been to this tunnel and no what I mean? And do you think it will be a DLC location? Or am I just over evaluating a random detail in the train line?

Yep, that's the suspected entry point for Old World Blues. There's a video out somewhere of a crashed satellite or something projecting onto the screen of the old drive-in theater nearby, and that locale's proximity to the theater suggests that it is the entry point for OWB.

The Mojave Drive-In, that's it. Nothing more.

no I am talking about the tunnel on the tracks south of that, go there and then follow the tracks south and you will see a segment veer off into a blocked tunnel. and there is a lottery ticket at the entrance.