Billie first appears when Lewis and Bud arrive to find her and Gaston about to race. Gaston asks Lewis to time the short race, which he manages to win.
Besides her full scale model train utilized in the race, Billie also has a small train used to pass trays around the dinner table. When Tiny is on the attack, she utilizes her train to ram the dinosaur back outside.
In the video game, Wilbur is charged early on with helping Billie restore the power-charger for her large trains. Billie also operates a monorail line that allows Wilbur to travel to different parts of the city that has a station right inside the foyer of the house.
Billie originally switched her accents constantly, before Lewis finally asks where she comes from: Cleveland.
It was Billie who told Lewis (and the audience) that "from failing you learn, from success not so much." This may also imply to the fact that many famous people, including Walt Disney, came across even many failures before they became successful.