Here's a big one....
That Jesus used the name "Jehovah" when he prayed.
Really? Where? Sure, the Lord's prayer has "Hallowed be thy name," but he didn't utter Jehovah or Yahweh there. Nor did he utter the name "Jehovah" in John chapter 17 when he prayed that he made God's name manifest. Jesus NEVER utters "Jehovah" in ANY of his prayers that are recorded in the New Testament, even in the New World Translation. So, apparently, when he used "name" in those passages he was not referring to pronouncing the name, but was referring to the concept of what a name represents.
In fact, even though the NWT "restores" the name Jehovah to the NT (with absolutely no Greek manuscript support!), Jesus only utters the name "Jehovah" in the NWT just three times when he's not quoting Old Testament passages. All the other places where the NWT has Jesus uttering the name Jehovah are quotations from the Old Testament.
But, in reality, there is actually not one Greek manuscript of the NT which has Yahweh or Jehovah in it in Greek or Hebrew letters. Just check the Greek text of the Kingdom Interlinear to confirm that one. So, one of the JWs biggest doctrines (that Christians must use the name "Jehovah" to be saved) is not in the Bible!