Contradiction with Numbers 4:15
Numbers 4:15 states only the sons of Kohath could handle the holy items, contradicting Numbers 3:31 where it implies oversight was shared with Aaron and his sons.
Numbers 4:15: And when Aaron and his sons have made an end of covering the sanctuary, and all the vessels of the sanctuary, as the camp is to set forward; after that, the sons of Kohath shall come to bear [it]: but they shall not touch [any] holy thing, lest they die. These [things are] the burden of the sons of Kohath in the tabernacle of the congregation.
Contradiction with Exodus 40:3
This verse requires Aaron to set up the testimony in the tabernacle, which Numbers 3:31 attributes to the Levites under Ithamar's supervision.
Exodus 40:3: And thou shalt put therein the ark of the testimony, and cover the ark with the vail.
Contradiction with 1 Kings 8:6
Here, the Ark is brought in by priests, not by Levites as mentioned in Numbers 3:31, showing a division in who actually handled the most holy things.
1 Kings 8:6: And the priests brought in the ark of the covenant of the LORD unto his place, into the oracle of the house, to the most holy [place, even] under the wings of the cherubims.
Contradiction with Numbers 7:9
Instructs that no wagons or oxen were given to the Kohathites, who carried the holy items on their shoulders, contrasting with the apparent shared responsibility in Numbers 3:31.
Numbers 7:9: But unto the sons of Kohath he gave none: because the service of the sanctuary belonging unto them [was that] they should bear upon their shoulders.