I was looking out the windows of elevated rapid transit today, watching the rain run down the window. something struck me as odd... the water running down the window was travelling in the same direction as the transit vehicle, against the force of the wind and the direction that physics would suggest it should go from both friction, and gravity. the vehicle is basically a rectangular cube. anyone want to try to duplicate this oddity?

Well, even though I'm not a physicist or an aeronautical engineer I have a plausible guess to why the water is going forward. Simply put - some form of turbulence is creating a standing wave type pressure pattern over the railcar. Since the pressure from such a thing is greater to the back of the window than the front... Well, like you said it'd be interesting to model. Too bad I don't know how. I've even seen something similar to this when driving my car. A low-pressure pocket caused by the front roof pillar sticking into the slipstream will suck the rain forward and upward. Also I'm willing to bet if you went to a different spot in the railcar, the rain might be moving in a different direction against the glass.

possibly vacum created in that area

yup, a vortex, created by the front end pushing the air aside, created turbulence alongside the vehicle, this created a vacume right near the front so the air further back moved forward to fill it.