We had the following to occur. Blue placed a tile which completed a line running from a Yellow station to a Red station. We know Blue doesn't score the points, but who does, Red or Yellow (or no one)? Would it be determined by which side of the station the line connected to, Departure or Inbound?
Make sure your trains are all placed on the same side of the stations. Trains should not be able to "run into each other" on the same track; that is, one side of the station has a train, the other side has a terminus for another train.