I added some of my own touches, including a second level with spiral staircase and a change from yellow to blue for the color scheme.
The rear of the bus features a slightly hidden spare tire behind the stairs.
The model has a opening entry / exit door at the front of the bus and each level comes off individually.
The staircase is attached at two points: a four-stud connection to the second level, and a single stud to the lower level. The staircase comes off easily when needed, but is sturdy enough not to fall off at the wrong time.