[21a - 47 lines; 21b - 46 lines]
We recommend using the textual changes suggested by the Bach and the marginal notes of the Vilna Shas. This section is devoted to any other important corrections that Acharonim have pointed out in the Gemara, Rashi and Tosfos.
 Gemara 21a [line 38]:
The words "Chazi Lah" חזי לה
should be "Chazi Lei" חזי ליה
This is the Girsa of Dikdukei Sofrim #7 and of Rashi. Similarly, this should be the Girsa in the next line, "ka'Matzne'a Lei" קמצנעא ליה.
 Gemara 21b [line 7]:
The words "Rav Chiya bar Yosef Amar Rebbi Yochanan" רב חייא בר יוסף אמר רבי יוחנן
should be "Rav Chiya bar Yosef Amar Rav" רב חייא בר יוסף אמר רב
This is the Girsa in the Gemara Pesachim 7a. The Girsa of Dikdukei Sofrim #40 and Rabeinu Chananel is also "Rav."
1)[line 1]אין הכרעת שלישית מכרעתEIN HACHRA'AS SHELISHIS MACHRA'AS (KOL MAKOM SHE'ATAH MOTZEI SHENAYIM CHALUKIN V'ECHAD MACHRI'A, HALACHAH K'DIVREI HA'MACHRI'A)
(a)When three opinions are expressed regarding a law, and one of them accepts parts of both other opinions as law, then the Halachah follows that opinion.
(b)If the intermediate opinion is independent of the other two; that is, it is not based on a dichotomy hinted at by the first two opinions, then the Halachah does not necessarily follow that opinion (RASHI).
2)[line 9]האי מודה רבי אליעזר לרבי יהושעHAI MODEH REBBI ELIEZER L'REBBI YEHOSHUA- This same question may be asked upon the Beraisa cited earlier (20b) regarding a barrel of oil which broke (Rashi 20b DH Modeh).
3)[line 13]בכלי שתוכו טהור וגבו טמאB'CHLI SHE'TOCHO TAHOR V'GABO TAMEI- The Gemara answers that the acquiescence mentioned in this Beraisa is not in the disallowance of actively being Metamei Terumah, but rather in the allowance of saving a Revi'is of Terumah. The discussion revolves around a Kli that is Tamei on the outside but not the inside. (This is only possible with a Tum'ah d'Rabanan; mid'Oraisa either the whole Kli is Tahor or the whole Kli is Tamei.) Even Rebbi Eliezer, who does not allow one to be actively Metamei Terumah for any reason, is not concerned that in this case the wine of Terumah will touch the outside of the Kli.
PEREK #2 KOL SHA'AH
4)[line 19]יסיקYASIK- start a fire with
5a)[line 19]תנורTANUR- an oven
b)[line 19]וכיריםKIRAYIM- a stove
6a)[line 21]מפררMEFARER- crumble it
b)[line 21]וזורה לרוחV'ZOREH LA'RU'ACH- and scatter it to the wind
7)[line 38]משייראMESHAIRA- (it) leaves over
8)[line 38]חזי להCHAZI (LAH) [LEI]- the owner sees it (the Chametz)
9)[line 38]אבל חיה דאי משיירא קמצנעא להAVAL CHAYAH D'IY MESHAIRA KA'MATZNE'A (LAH) [LEI]- a Chayah, however, who hides its leftovers... This poses two possible problems: (a) One may transgress Bal Yera'eh and Bal Yimatzei, and (b) one may accidentally eat the Chametz on Pesach (see Insights)
10)[line 1]כותחKUTACH- a dip prepared by cooking whey with stale bread and salt. Rebbi Yehudah ben Beseira agrees with Beis Shamai. Kutach is eaten as a condiment and does not spoil easily, and is therefore consumed slowly. This view maintains that from the time that one has an obligation to perform a Bedikah he must be sure that Chametz in his possession at that time does not remain in the world over Pesach.
11)[line 3]שחרכוSHE'CHEIRCHO- he charred it (rendering it inedible)
12)[line 9]בחיטי קורדניתאB'CHITEI KURDANYASA- with [the extremely tough] wheat of Cordyene (a district lying to the east of the Tigris River, south of Armenia) [that came into contact with water]
13)[line 16]לא יאכל חמץLO YE'ACHEL CHAMETZ- From that which the Torah does not write "Lo Sochelu Chametz" (or something along these lines), Chizkiyah infers that even that which is the step prior to eating — i.e., deriving pleasure, which is worth money to buy food — is prohibited.
14)[line 24]לגרLA'GER- to a Ger Toshav (a Nochri who has accepted upon himself to observe the seven Mitzvos given to Noach and all of his descendants. These do not include the prohibition against consuming meat from an animal which was not slaughtered.)
15)[line 37]דגר אתה מצווה להחיותוGER, ATAH METZUVEH L'HACHAYOSO- one is commanded to sustain and support a Ger Toshav (Vayikra 25:35)
16)[last line]"לכלב תשליכון אותו""LA'KELEV TASHLICHUN OSO"- (Shemos 22:30) - The Torah commands one not to eat a Tereifah, but rather to throw it to the dogs.