Also in advance: Make fondant letters. Tint 1 oz. each green, orange, violet, yellow, red and blue. Roll out 1/8 in. thick. Cut letters using cutters from set. Let dry on cornstarch-dusted board.
Bake and cool two 1-layer sheet cakes and 16 mini cupcakes. Trim 1 in. off each sheet cake then set cakes side-by-side on wrapped board to create a 22 x 14 in. rectangle.
Tint fondant: 90 oz. blue, 20 oz. gray. Roll out 1/8 in. thick as needed. Prepare and cover cakes with blue rolled fondant. Cut a 22 x 5 in. curve for track; attach using damp brush. Pipe tip 3 curved outline details. Cover mini cupcakes with tip 12 swirls for smoke effect. Position mini cupcakes, letters and candy plaque. Pipe tip 12 large bead ?smoke? bottom border.