Contradiction with Genesis 15:18
This verse promises a vast land to Abraham's descendants; Joshua 19:23 describes a smaller, specific allotment.
Genesis 15:18: In the same day the LORD made a covenant with Abram, saying, Unto thy seed have I given this land, from the river of Egypt unto the great river, the river Euphrates:
Contradiction with Numbers 34:2
Lays out different boundaries for the land of Israel compared to Joshua 19:23's settled portion.
Numbers 34:2: Command the children of Israel, and say unto them, When ye come into the land of Canaan; (this [is] the land that shall fall unto you for an inheritance, [even] the land of Canaan with the coasts thereof:)
Contradiction with Deuteronomy 11:24
Mentions land spanning from wilderness to Euphrates, larger than described in Joshua 19:23.
Deuteronomy 11:24: Every place whereon the soles of your feet shall tread shall be yours: from the wilderness and Lebanon, from the river, the river Euphrates, even unto the uttermost sea shall your coast be.
Contradiction with 2 Samuel 8:3
Suggests territorial control extending beyond what's captured by Joshua 19:23.
2 Samuel 8:3: David smote also Hadadezer, the son of Rehob, king of Zobah, as he went to recover his border at the river Euphrates. [Hadadezer: or, Hadarezer]
Contradiction with Joshua 21:43
States all land was given to Israel, while Joshua 19:23 refers to a specific allocation to one tribe.
Joshua 21:43: And the LORD gave unto Israel all the land which he sware to give unto their fathers; and they possessed it, and dwelt therein.