Set the speed throttle at 100 to get Duck going. Click the lever (the red thing) to switch the points. Press the D key to move Duck manually. He sometimes derails.
This was originally supposed to feature @7andrian2018's Gordon sprite, but because of the sharp turns, it was hard to get him to stay on the tracks, so I switched it to Duck. Gordon will be in the next one, though! (Added a lever!)