Nothing is really out of the question in a drawing, HOWEVER, a picture should leave more to the viewer's imagination than spelling things out for them explicitly. The more explicit, the less a viewer's imagination is engaged. And it is the viewer's imagination that you're after. You're not drawing them a map that forces them to a destination of your choice. They should arrive in the general vicinity of what you had in mind mostly on their own. You just provide some guideposts.
The SUGGESTION of something in many many cases can be better than the thing itself.
For instance, a bird can suggest sound -- a bird's song -- which is why there are many scrolls with birds--they double (or even triple) up on meaning. Different KINDS of birds can also suggest season and location without any other information. A goose and the moon suggest autumn. A swallow suggests summer...--even in the West.
Water can also suggest sound, as well as a certain kind of environment.
Insects also make noise, sometimes at specific times of the year. A cricket depicted in a drawing with the moon and grass suggests chirping and breezes on an autumn night (Even if you're not Japanese). A cicada suggest sound also and scroll drawings depicting the insect are meant to evoke its song on a summer day.
Restraint and more restraint is a key to good display. Like the negative spaces in a tree's design, its off-center placement in the pot, or the blank spaces in a scroll drawing, a good display allows the VIEWER to construct a mental image. The more stuff you overtly include limits that ability.