Contradiction with Genesis 15:18
Genesis 10:28 lists the descendants of Joktan, suggesting different boundaries for the land from those described in God's covenant with Abram in Genesis 15:18.
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 Exodus 23:31
Genesis 10:28 suggests settled territories of early peoples, while Exodus 23:31 gives different geographic boundaries promised to the descendants of Abraham.
Exodus 23:31: And I will set thy bounds from the Red sea even unto the sea of the Philistines, and from the desert unto the river: for I will deliver the inhabitants of the land into your hand; and thou shalt drive them out before thee.
Contradiction with Numbers 34:2-12
Genesis 10:28 describes descendants and their lands, which can conflict with the specific land boundaries given to the Israelites in Numbers 34:2-12.
Numbers 34:2-12: 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 1:7-8
Genesis 10:28 gives a lineage which implies settlement areas, while Deuteronomy 1:7-8 outlines specific lands for Israel differing from those implied settlements.
Deuteronomy 1:7-8: Turn you, and take your journey, and go to the mount of the Amorites, and unto all [the places] nigh thereunto, in the plain, in the hills, and in the vale, and in the south, and by the sea side, to the land of the Canaanites, and unto Lebanon, unto the great river, the river Euphrates. [all...: Heb. all his neighbours]
Contradiction with Joshua 1:4
Genesis 10:28 talks about descendants' lands, which can contrast with geographic boundaries offered to Israelites in Joshua 1:4.
Joshua 1:4: From the wilderness and this Lebanon even unto the great river, the river Euphrates, all the land of the Hittites, and unto the great sea toward the going down of the sun, shall be your coast.