Contradiction with Joshua 11:23
This verse states that Joshua took the whole land according to what the Lord had spoken to Moses, which may contradict the specific allocation mentioned in Joshua 21:11.
Joshua 11:23: So Joshua took the whole land, according to all that the LORD said unto Moses; and Joshua gave it for an inheritance unto Israel according to their divisions by their tribes. And the land rested from war.
Contradiction with Deuteronomy 10:9
This states that the Levites have no inheritance with their brethren, as the Lord is their inheritance, which could contradict the Levites receiving Hebron in Joshua 21:11.
Deuteronomy 10:9: Wherefore Levi hath no part nor inheritance with his brethren; the LORD [is] his inheritance, according as the LORD thy God promised him.
Contradiction with Joshua 14:13-14
Caleb is given Hebron as his inheritance, which might conflict with the allocation of Hebron to the Levites in Joshua 21:11.
Joshua 14:13-14: And Joshua blessed him, and gave unto Caleb the son of Jephunneh Hebron for an inheritance.
Contradiction with Numbers 35:2-3
Levites are to receive cities and suburbs instead of inherited land; the specific mention of 'inheritance' in Joshua 21:11 may seem at odds.
Numbers 35:2-3: Command the children of Israel, that they give unto the Levites of the inheritance of their possession cities to dwell in; and ye shall give [also] unto the Levites suburbs for the cities round about them.
Contradiction with Judges 1:20
Hebron is given to Caleb, consistent with God's promise, which contrasts with its mention as a Levitical city in Joshua 21:11.
Judges 1:20: And they gave Hebron unto Caleb, as Moses said: and he expelled thence the three sons of Anak.