Contradiction with 1 Chronicles 7:6
1 Chronicles 7 specifies different numbers and potentially different descendants for the tribes compared to Numbers 26:27.
1 Chronicles 7:6: [The sons] of Benjamin; Bela, and Becher, and Jediael, three.
Contradiction with 1 Chronicles 2:9
The genealogy and numbers of families listed in Chronicles sometimes differ from those in Numbers.
1 Chronicles 2:9: The sons also of Hezron, that were born unto him; Jerahmeel, and Ram, and Chelubai. [Ram: Gr. Aram] [Chelubai: or, Caleb]
Contradiction with Genesis 49:13
Although not directly a numerical contradiction, the future of the tribe of Zebulun described here can be interpreted as different from the situation in Numbers 26:27.
Genesis 49:13: Zebulun shall dwell at the haven of the sea; and he [shall be] for an haven of ships; and his border [shall be] unto Zidon.
Contradiction with Judges 1:30
This verse talks about the Tribes not driving out their inhabitants which can be seen as contradictory to the fully accounted families suggested in Numbers 26:27.
Judges 1:30: Neither did Zebulun drive out the inhabitants of Kitron, nor the inhabitants of Nahalol; but the Canaanites dwelt among them, and became tributaries.