Gittin 27: A Shaliach's Worst Nightmare?

What happens if the shaliach for a get loses the get? It depends how much time passes before he finds it, assuming he does. Could the get have been replaced in the interim, for example? What happens if the players in the get have the same names as others who are getting divorced. Also, Rabbi Zeira finds a contradiction to our mishnah in a baraita. Which turns out to be a bit lesser as compared to a mishnah contradicting a mishnah... But the baraita is the clearer contradiction this time. Which helps clarify the halakhah here, including how long a get can be lost without it becoming problematic.