Y'know, Donald may have a speed impediment, but he still knows how to pronounce things properly.
His adventure at Castaway Cay reminds me of the issue of the proper pronunciation of "Cay" in "Castaway Cay". A lot of people pronounce it as "Kay", as in Mary Kay. But if you have seen shows on TV related to Disney cruises, you would have heard that it is pronounced as "key".
A quick look online at the Miriam-Webster website seems to indicate that "key" might be the preferred pronunciation, while "kay" might still be acceptable. The words they listed that rhymes with "cay" all seem to rhyme with "key". Yet, in the audio part, both "key" and "kay" are listed (very confusing).
I'm going to stick with "key" because that is how it has been referred to officially.