Matthew
This page discusses issues particular to the gospel of Matthew:
The Not So Great Omission: The Great Omission is the name generally given to a section of Mk (approximately 75 verses long) that has no parallel in Lk. It is not generally known that that almost half of the verses in this same section of Mk either have no parallel in Mt either, or are significantly shorter in Mt. This suggests there could have been a reason common to Mt and Lk for this text to be not present.
The Gospel of the Ebionites: This gospel is one of possibly three gospels, orignally written in either Hebrew or Amanaic, that may be associated with The Gospel of the Hebrews, believed by some to be the original form of Matthew's gospel.