At MK, there are bathrooms to the right of the ticketing/guest relations windows, but that is outside the turnstile area (between bag check and turnstiles). I can't think of any that are IN the area where you watch the opening RD show.
DHS there are bathrooms outside the turnstiles, on the left when facing the entrance, heading down the sidewalk to/from the parking lot.
Those are the only 2 things that I can think of, that I know. Others may know more.