I'm not sure if this is trope-worthy, but it's an idea, anyway.
I'm wondering if it could be a trope that a lot of writers mix up Arabs and Muslims, disregarding the fact that there are many predominately Muslim ethnic groups that are not related to Arabs and do not speak Arabic - Turks, Iranians, Kurds, Kazakhs, et cetera. A related idea is the confusion of Arab cultural practices with things required by the Koran (I believe that having women cover their faces is an example). Subtrope of Did Not Do The Research
We touch on this a bit in the beginning of Middle Eastern Coalition
, but I'm wondering if it might be worthy of its own trope.