Well I hate to be the bearer of bad news, but such inconsistencies could indeed rub some folks the wrong way, so you could lose some "points" for attention to detail. On the other hand, in my experience, I have seen such mistakes be forgiven or overlooked. It really depends on two factors: 1) how strong is your candidacy (if you are marginal, it could be detrimental, if you are strong, it will probably not be enough to cause problems). and 2) how much of a stickler is the person who reads your essays. If you get invited for an interview, you might use it as an opportunity to at least acknowledge that you realized the font was inconsistent after you uploaded and due to the system you were using, it was not evident before you uploaded (?)