Hmm... that's an interesting one. I'm poking around this one just because I find stuff like this interesting.
The character in the file itself is DEFINITELY a C--if you open the file in a raw text editor, as portent did, it's a C. If you copy it and paste it anywhere else, it's a C.
It's definitely something Word is doing; if you type a C over it it looks fine until you save--then it turns back into an A. If you add one or more spaces before it, then save, it will turn into all manner of other letters--R, I, T, E, S, and even a C like it's supposed to.
Since copying the text into a new document doesn't replicate the error but copying the whole single-cell table brings the weird character over, that narrows it down to either a really weird Word bug, or something wrong with that table in Word's internal system.
I've seen "paragraphs of death" that had gotten internally corrupted such that you could view them fine, but any document that contained the paragraph would crash word upon saving. Generally speaking you can clear that up if you do a save as, if you can get Word to save without crashing. No such luck here--it carries through save as operations.
I'd be really interested in finding the actual cause, but I'm going with Word bug at this point.
Probably related: There appears to be several blank lines then Page and Page 2 below that table in the file itself, and that's what Text Edit shows when it opens it.
Anyway, interesting.