1) The Magen Avraham holds that since the intermediary blessing in both the afternoon and evening Shemoneh Esreh begin with the word ''You'', there is no indication in his words that one actually forgot it was Shabbat, and therefore one doesn't have to complete the weekday blessing. The Shulchan Aruch, on the other hand, holds that if one indeed forgot it was Shabbat and intended to say the weekday blessing, then one must complete the weekday blessing, even during Shabbat afternoon and evening prayers (O.H 268:2 and Mishna Berurua). 2) However, if one said both words, ''You favor man'', even though one was aware it was Shabbat and did so only out of habit, one must nevertheless complete the weekday blessing.

1) There are certain errors in the Shemoneh Esreh, such as the one discussed above, whereby once one has completed the Shemoneh Esreh without correcting the error, one must go back and repeat the entire Shemoneh Esreh from the beginning. The question is: at what point exactly is one considered to have completed the Shemoneh Esreh? Most authorities agree that the supplication we say after the Shemoneh Esreh, i.e., ''My G-d, guard my tongue'' is considered to be an extension of the Shemoneh Esreh in the sense that one would not have to return to the beginning as long as one has not completed that prayer. The Kitzur Shulchan Aruch, as we see above, holds that once one has started the verse ''may it be Your will'', the Shemoneh Esreh is over, and one must go back and repeat the whole thing. However, the Mishna Berurah (118:18) seems to hold that until one has completed that verse, one does not have to go back to the beginning. Nevertheless, the Mishna Berura does hold that once one has completed that verse, one must return to the beginning, even though one has not yet taken the three steps backwards.

אם לא נזכר עד בברכות האחרונות דהיינו מן רצה ולהלן פוסק באמצע ברכה במקום שנזכר ומתחיל בשל שבת או יום טוב וגומר כסדר ואם לא נזכר עד לאחר שהתחיל לומר יהיו לרצון חוזר לראש התפלה

1) There is another opinion brought by the Shulchan Aruch (O.H 268:2) which holds that there is no difference between the additional prayers and the Shabbat Shemoneh Esreh regarding this particular Halacha. However the Mishna Berura (268:5) writes that according to the Acharonim (Bach, Eliyah Rabbah), one should follow the opinion which rules that if the error occurs in the additional prayers, one should stop in the middle of the blessing, because completing it might constitute a violation of the prohibition against saying an unnecessary blessing.