According to Osho, an accident is the unforeseen event itself (the car skids and crashes). Misfortune is the unfortunate outcome or who it harms (the driver dies while the ministers live—bad for the country). A bad day is the lingering annoyance it creates afterward (waking to their faces in every newspaper). He uses humor to show scale: occurrence, consequence, and mood.
Accident is what happens, misfortune is how badly and to whom it turns out, and a bad day is how it spoils your mood afterward.