Ngineer: If you keep the wheels and track really clean (and also the contact strips above the trucks and the bearing cups in the trucks) then the LEDs will not flicker. The contact strips and cups stay clean for long perods but track/wheels need regular cleanings.
Max:I was not privy to your PMs with Al about the resistors, but that is a moot point; See beleo.
Al: I can't hold myself back any longer. You sure are "Mr. Vague: when asking for help here. SInce you are dabbling with electrical and electronic circuits, it wouldn't hurt to learn some basic terminology like "serial" and "parallel" connections.

Your lengthy description of the circuit you created coudl have been much shorted and clearer if you only used those terms. All you needed to say to very clearly describe your circuit was: the 2 resistors and the bulb are all connected in-series. That short sentence clearly and unambiguously describes what you did.