1) STEPPING OUT OF THE "IR MIKLAT"
OPINIONS: Mar Zutra bar Tuvya states in the name of Rav that when an accidental killer steps out of the boundary of the Ir Miklat before his trial, the Go'el ha'Dam may not kill him. He derives from the verse that the Go'el ha'Dam may not kill the accidental killer until the killer is brought before the court. (According to the RITVA, this means that the Go'el ha'Dam may not kill the accidental killer until the court warns the killer that if he exits the Ir Miklat, the Go'el ha'Dam will have the right to kill him.) If the Go'el ha'Dam kills him before he is brought before the court, then the Go'el ha'Dam is punished as a murderer.
Earlier (10b), Rav Huna states that when an accidental killer flees to an Ir Miklat and the Go'el ha'Dam kills him before he reaches the city, the Go'el ha'Dam is not punished by Beis Din as a murderer. Does Mar Zutra bar Tuvya disagree with Rav Huna?
(a) The RE'AH and RABEINU MEIR HA'LEVI, cited by the RITVA, maintain that Mar Zutra disagrees with Rav Huna. Rav Huna says that if the Go'el ha'Dam kills the accidental killer on the way to an Ir Miklat, he is not killed by Beis Din. It follows that, according to Rav Huna, the same applies if the Go'el ha'Dam kills the accidental killer when he steps outside of the Ir Miklat. Rav Huna's opinion is that of Rebbi Yosi and Rebbi Akiva, and the Halachah therefore follows his opinion.
(b) The RITVA argues that the two statements are not exclusive. Rav Huna might agree that once a killer has reached the Ir Miklat and now is considered a permanent resident of that city, the Go'el ha'Dam is forbidden from killing him even if he steps outside of the city limits. (Consequently, it is possible that Rav Huna is not following the view of Rebbi Akiva and Rebbi Yosi. They say only that the Go'el ha'Dam is not punished when he kills the killer who negligently strays outside of the city limits. Perhaps they do not condone the Go'el ha'Dam's killing of the accidental killer before he even has a chance to reach the Ir Miklat.) Moreover, if Rav Huna's view is not in accordance with this Tana, then the Gemara should have mentioned this earlier when it questioned Rav Huna's opinion; the Gemara should have answered its questions by saying that Rav Huna's opinion is the opinion of other Tana'im. This omission proves that they do not necessarily have the same opinion.
(RASHI seems to make a similar distinction between the case of Rav Huna and that of Mar Zutra. Rashi adds that Rav Huna's case is "on the road on the way [to an Ir Miklat]." The HAGAHOS HA'BACH (10b) points out that Rashi adds "on the way [to an Ir Miklat]" to show that this is not similar to the case later in which the killer steps out of his city when he is not "on the way.")
The ARUCH LA'NER and SI'ACH YITZCHAK assert that the RAMBAM understands the Gemara as the Re'ah does (in (a) above). The Rambam (Hilchos Rotze'ach 5:10) rules that if the Go'el ha'Dam kills the accidental killer at any time after the accidental killing, he is innocent. The KESEF MISHNEH gives many reasons for why the Rambam chooses not to rule like Rav, who maintains that the Go'el ha'Dam is punished if he kills before the trial. One reason is the fact that, in this case, Rav follows the opinion of Rebbi Eliezer who is from the school of Beis Shamai (and whom the Halachah does not follow).
The Aruch la'Ner and Si'ach Yitzchak explain that the Rambam understands, as the Re'ah does, that Mar Zutra in the name of Rav disagrees with Rav Huna. The Rambam rules like Rav Huna, since he was a later Amora than Rav. (The Kesef Mishneh does not give this answer, presumably because he understands the Gemara as Rashi and the Ritva explain, and he maintains that Mar Zutra in the name of Rav does not disagree with Rav Huna.)
(c) RABEINU CHANANEL seems to have a third approach to the Sugya. According to Rabeinu Chananel, both the Mishnah and Rav in the Gemara discuss a Go'el ha'Dam's right to kill an accidental killer before the court has decided that he is guilty of killing b'Shogeg. The Mishnah earlier (9b) teaches that even before the case is brought before the court, the killer must flee to an Ir Miklat. Rebbi Akiva and Rebbi Yosi permit the Go'el ha'Dam to kill the killer even though the court has not yet rendered any decision in the case. Rebbi Eliezer argues that until the court decides that the person has killed b'Shogeg, the Go'el ha'Dam has no right to kill the killer.
According to this explanation, it is clear that even Rebbi Eliezer agrees that the Go'el ha'Dam may kill the killer after Beis Din has established that he killed b'Shogeg. That is the case in which Rav Huna earlier rules that the Go'el ha'Dam is exempt for killing the accidental killer.
2) TO WHERE MAY A LEVI FLEE
OPINIONS: The Mishnah discusses the question of where a Levi flees if he kills accidentally. The question is based on the fact that all of the Arei Miklat belong to the Leviyim. The Arei Miklat are the cities that were designated for the Leviyim. Since the Leviyim own the Arei Miklat, how is it possible for a Levi to be in "Galus," in exile, while in his hometown? The Mishnah explains that a Levi who kills accidentally must go from one Ir Miklat to another Ir Miklat.
The Gemara cites a Beraisa which states that a Levi who stays in his own city is also protected from the Go'el ha'Dam. The Beraisa seems to contradict the Mishnah, which implies that Levi may not stay in his own town. How is the statement of the Beraisa to be reconciled with the Mishnah?
(a) TOSFOS (here and in Zevachim 117a) and RASHI (Zevachim 117a) explain as follows. A Levi who killed accidentally has two options: he may go to another city, where he will be free to roam anywhere within the city limits, or he may stay in his own city and move to another neighborhood in his city. If he chooses the second option, however, his movement in the city will be limited. How limited will he be? The ME'IRI cites two opinions. According to one opinion, he will be confined to a single neighborhood within the city (as TOSFOS and the TOSFOS SHANTZ here imply). According to another opinion, he will be able to roam around the entire city except for his original neighborhood (as Tosfos in Zevachim implies; see also ARUCH LA'NER here).
Accordingly, the Mishnah is expressing one option, while the Beraisa is expressing another option.
(b) Tosfos in Zevachim and the RITVA here answer that l'Chatchilah a Levi should flee to a different city. However, b'Di'eved, if he flees to his own city, he will be protected there.
The SHEYAREI KORBAN (Yerushalmi Makos 2:6) asks, how can there be a ruling of "l'Chatchilah" and "b'Di'eved" with regard to such a matter? The killer is seeking refuge from a Go'el ha'Dam by fleeing to the Ir Miklat. He will be putting his life in danger by going to another city, and he certainly should be permitted to remain where he is l'Chatchilah in order to save his life and avoid putting his life in danger.
Perhaps Tosfos means that if the killer wants a greater Kaparah, he should go to another city despite the risk to his life, instead of remaining in his own city.
(c) The RAMBAM (Hilchos Rotze'ach 7:5) and ME'IRI have a different understanding of the Mishnah and Gemara here. The Rambam apparently learns that when the Beraisa says that the Levi is protected when he stays in his hometown, it refers only to when he killed outside of his hometown. However, when he killed within his own town, he must fulfill the words of the Mishnah and flee to another city to seek refuge. In such a case, his hometown does not provide refuge for him. (Y. MONTROSE)