Contradiction with Exodus 33:20
Leviticus 9:23 describes the presence of the Lord appearing to all the people, whereas Exodus 33:20 states that no one can see God's face and live.
Exodus 33:20: And he said, Thou canst not see my face: for there shall no man see me, and live.
Contradiction with John 1:18
Leviticus 9:23 implies that the presence of God was visible to the people, while John 1:18 says no one has ever seen God.
John 1:18: No man hath seen God at any time; the only begotten Son, which is in the bosom of the Father, he hath declared [him].
Contradiction with 1 Timothy 6:16
Leviticus 9:23 shows God appearing to all the people, but 1 Timothy 6:16 mentions that God dwells in unapproachable light, whom no one has seen.
1 Timothy 6:16: Who only hath immortality, dwelling in the light which no man can approach unto; whom no man hath seen, nor can see: to whom [be] honour and power everlasting. Amen.