And I came across this pdf, הלכות רב אלפס, on Gittin. I think has different pagination that the Rif in our gemaras, but it strikes me as useful. You get to compare our text with their text, to see that it is the same or different; there are sometimes gaps indicating change of topic; and you have convenient access to the Ran while sitting in front of the computer. And this is useful to me, as I post to my Rif Yomi blog.
Here is the first page of the Rif on Gittin. I am not sure who made the emendations -- the printer, or perhaps some shnook, so this is something to keep in mind. But anyway, there are some interesting features just on this first page.
The emendation on the bottom of the page is no doubt correct. While Rava sometimes switches for Rabba, our girsa in the gemara, and our girsa in the Rif in our gemara (see here), has Rabba. And indeed, this is a machlokes, and on the next page in the Rif (even in this printing) Rava argues with this first speaker. So it must be Rabba.
The emendation in the middle of the page is more interestin. There is a gap, followed by והמוליך והמביא ממדינה למדינה במדינת הים. Though there seems not to be a vav there in והמביא, such that it is simply המביא. This gap might indicate a new statement. But note the mark after והמוליך to mark it off. But then, someone inserted a two-letter word in between והמביא and ממדינה. It is hard to make out. The first letter seems to be a gimmel while the second letter seems to be an aleph. But this makes no sense. I would guess the second letter is really a tes. Then, the inserted word is get.
But why should that word get be inserted? The answer, I think, lies in the (accidental) gap, or in the lack of vav in והמביא.
The way one is supposed to read the Mishna (and so does e.g. Rashi read) is with והמוליך as attached to the previous sentence. Thus, not only one who brings from an overseas country (to Eretz Yisrael), but also one who takes it (from Eretz Yisrael to an overseas country). Meanwhile, והמביא (or perhaps without the vav) is the beginning of a separate statement. This may or may not be part of the statement of the Chachamim.
And, as the beginning of a separate statement, one might expect to have get there to explain what is being brought. Indeed, looking to the Yerushalmi Gittin 4b, I would point out the following statement from Rabbi Leizer, which does not have the vav in hameivi, and does indeed have the word get:
מתיב רבי לעזר לרבנן כמא דאית לכון המביא גט ממדינה למדינה במדינת הים צריך שיאמר בפני נכתב ובפני נחתם. אף אנא אית לי המביא ממדינה למדינה בא"י צריך שיאמר בפני נכתב ובפני נחתם.
This is not in the Mishna as printed in our Yerushalmi, but it might well have been in the Mishna back then.
If so, this would imply that this is not some accidental emendation by some shnook, but rather making the text comply with a version of the Mishna as reflected in the Yerushalmi. Indeed, the Rif's girsa of the Mishna is (often?) the girsa of the Geonim, and often reflects the Mishna as found in the Yerushalmi.