Contradiction with Exodus 32:1
Contradicts by showing that Moses was associated with the people who were impatient and unfaithful when Moses delayed to come down from the mount.
Exodus 32:1: And when the people saw that Moses delayed to come down out of the mount, the people gathered themselves together unto Aaron, and said unto him, Up, make us gods, which shall go before us; for [as for] this Moses, the man that brought us up out of the land of Egypt, we wot not what is become of him.
Contradiction with Numbers 20:12
Shows Moses was not completely faithful, as God punished him for not believing and sanctifying Him before the Israelites.
Numbers 20:12: And the LORD spake unto Moses and Aaron, Because ye believed me not, to sanctify me in the eyes of the children of Israel, therefore ye shall not bring this congregation into the land which I have given them.
Contradiction with Exodus 4:10-14
Demonstrates Moses' initial reluctance and lack of faith in God's calling due to his speech difficulties.
Exodus 4:10-14: And Moses said unto the LORD, O my Lord, I [am] not eloquent, neither heretofore, nor since thou hast spoken unto thy servant: but I [am] slow of speech, and of a slow tongue. [eloquent: Heb. a man of words] [heretofore: Heb. since yesterday, nor since the third day]