1) Ch. 18, v. 2,3: "V'hi'nei shloshoh anoshim, Va'yomer A-DO-NOY" – And behold three men, And he said A-DO-NOY – There is a false theological concept of trinity, that there are three combined spiritual powers/beings that combine into becoming one deity, hence tri-nutty. They bring a proof from these two verses. Three people came in front of Avrohom and he addresses them as one and calls them a-do-noy, one. This cheap bit of theological logic is readily rebutted in numerous ways. How?
2) Ch. 18, v. 4: "V'hisho'anu tachas ho'EITZ" – And repose under the tree – Rashi says "tachas ho'ilon." Sifsei Chachomim explains that Rashi is forewarning that EITZ is actually wood, and thus seems to indicate a tree that was felled. ILON is a live tree. If so, why doesn't the verse say ILON?
3) Ch. 18, v. 9: "A'yei Soroh ishtecho" – Where is Soroh your wife – Why did the angels ask where Soroh was? Is this not contrary to the rule of the gemara Kidushin 70b, that one should not ask about the welfare of a woman even from her husband?
4) Ch. 18, v. 25: "Hashofeit kol ho'oretz lo yaa'seh mishpot" – Would the Judge of all the land not do justice – On a simple level we understand the words "hashofeit kol ho'oretz" in Avrohom's plea to mean that if we were dealing with a small-time judge who does not issue verdicts that are in line with justice, it would not be so startling, as he is not a major judge, and his influence is also limited. However, since Hashem is the Judge over the whole world, His not administering fair rulings is catastrophic. How can we explain these words in a different light and Avrohom's words would have a deeper meaning?
5) Ch. 21, v. 7: "Heinikoh vonim Soroh" – Soroh nursed children – Rashi questions the word "vonim," CHILDREN. Didn’t Soroh only nurse one child, her son Yitzchok? Rashi answers that the wives of the guests brought along their young nursing children. These women spoke negatively of Soroh, saying that she was too old to conceive and give birth to a child. No doubt she picked up a waif from the street. To counter this Soroh nursed their children, thus negating their negative assertion. Surely people spoke badly of Soroh before the occasion of this festive meal. If so, why did Soroh wait until now to nurse others' children