Contradiction with Joshua 13:1
This verse states Joshua was old and advanced in years, implying that most of the land had not been possessed yet, which contradicts the notion that Reubenites, Gadites, and half-tribe of Manasseh had already received their inheritance.
Joshua 13:1: Now Joshua was old [and] stricken in years; and the LORD said unto him, Thou art old [and] stricken in years, and there remaineth yet very much land to be possessed. [to...: Heb. to possess it]
Contradiction with Joshua 11:23
It is stated that Joshua took the whole land, yet in Joshua 13:8, it seems portioning out the inheritance is still ongoing, indicating some land was still unconquered.
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 Judges 1:27
Describes the failure of the tribe of Manasseh to drive out all the inhabitants, conflicting with the idea that their inheritance was fully received.
Judges 1:27: Neither did Manasseh drive out [the inhabitants of] Bethshean and her towns, nor Taanach and her towns, nor the inhabitants of Dor and her towns, nor the inhabitants of Ibleam and her towns, nor the inhabitants of Megiddo and her towns: but the Canaanites would dwell in that land.
Contradiction with Numbers 32:33
Suggests Moses gave land to the Reubenites, Gadites, and half-tribe of Manasseh, implying they had settled prior to the conveyance mentioned in Joshua 13:8.
Numbers 32:33: And Moses gave unto them, [even] to the children of Gad, and to the children of Reuben, and unto half the tribe of Manasseh the son of Joseph, the kingdom of Sihon king of the Amorites, and the kingdom of Og king of Bashan, the land, with the cities thereof in the coasts, [even] the cities of the country round about.
Contradiction with Deuteronomy 3:12-17
Provides details of land distribution by Moses, which can seem contradictory to Joshua 13:8, which describes a further allocation by Joshua.
Deuteronomy 3:12-17: And this land, [which] we possessed at that time, from Aroer, which [is] by the river Arnon, and half mount Gilead, and the cities thereof, gave I unto the Reubenites and to the Gadites.