Please read the narration which shows Abdullah bin Maso'od ( a great companion of The Holy Prophet) used to say that Mu'awwidhtain which are last two Surahs, these are no more part of The Holy Quran.

If two Surahs are excessively added in the Holy Quran, is it not a distortion in Quran?

http://sunnah.com/urn/46560

The verse of Rajam is missing from Quran

Please read another narration that Umar bin Khattab says the verse of Rajam is missing from Quran.

The Holy Prophet forgot the verses of Quran

Please read another narration which says that The Holy Prophet forgot the verses of Quran somebody else reminded him.

If we believe in such narrations, we don't know how many verses which were not reminded to the Prophet ! (astaghferullah)