I think that accusations against the Mormon Church are hardest to disprove when they are internalized in Church doctrine, or in other words when Church doctrine contradicts itself. Here are two such examples. Many many more coming soon:

2 Nephi 5:15 vs. 2 Nephi 5:16. Supporting scriptures are 1 Chronicles 22:14 and 1 Kings 5:13-16 which would be very hard to translate incorrectly due to external evidence. However the contradiction holds without them.

Moroni 10:3-5 vs. D & C 10:37. To say that these are consistent is to say that righteousness is a completely ambiguous property which is to deny Mormon 9:19

Note that I can't show contradictions between the Bible and LDS Scriptures or internal Biblical inconsistincies because Joseph Smith claimed something to the effect that he never finished correcting the Bible and Mormonism claims the Bible to be translated incorrectly originally or something similar to that.

Theoretically, I can't show contradictions in the Book of Mormon either because of Mormon 9:31-34. However if you read on I think you will agree that this does not account for the external inconsistencies in the Book of Mormon.

External Inconsistencies:All evidence is circumstantial, so to a true Latter-day Saint these won't matter, however there are some very large difficulties in treating the Book of Mormon as fact as Joseph Smith claimed. Check out this external link on it. I also plan to add information soon on the Mitochondrial DNA proof that Amerinds are not Middle-Eastern.