I am continuing to find a number of interesting features in Codex Vaticanus. The first example is taken from Matthew 3:7, the second is taken from Matthew 3:11-12.
If a word ends in a “Ν” and there is no room for it at the end of a line of text, then they place a makron over the last letter to signify its absence. This is what we have in the first image, γεννηματα εχιδνω[ν] τις υπεδειχεν υμιν φυ… Notice that the ν is not a part of the text. Instead, there is a macron/line over the ω. This seems to be a rather consistent practice.
Now look at the last letter on third from last line. It is a funky looking Κ. There is an extra line that cuts back toward the letter. This letter is an abbreviation for the word ΚΑΙ/και “and.” It seems to only appear that the end of a line.
Finally, I found another instance of the nomina sacra. The last three letters of line 8 (from the top) are ΠΝΙ with a macron overhead. This is the nomina sacra for Holy Spirit. Two features should be noted. First, the case of πνευμα “spirit,” dative, is maintained by the presence of the ΠΝΙ. Second, the next word ἁγιῳ “Holy” has not been abbreviated.