Here are a few I can think of:
-How wheelchair accessible are the pathways a client may need to traverse (e.g. loose dirt/sand paths, concrete walkways, gravel, steps, etc.)?
-Will the company support people in a variety of wheelchairs (i.e. manual, scooters, motorized, heavy/bulky motorized, with a tall backrest, etc.)?
-This can be a big deal-breaker for some: at anytime will the safari require clients to transfer out of their wheelchair?
-If a client can only walk short distances before resting, will there be enough opportunities to sit and rest?
-Will you support those with hearing impairments (partial or total deafness) and how (i.e. maybe a tour guide who knows ASL)?
-Is there a preferred part of the year when to visit (maybe cooler but not necessarily a monsoon season)?
-If the company provides food, will there be allergy-friendly options for those who cannot eat eggs/nuts/wheat/etc.?