Contradiction with Numbers 34:4
Numbers 34:4 describes the boundary of the land as going south of the ascent of Akrabbim, while Joshua 18:16 describes going down to the valley of the son of Hinnom.
Numbers 34:4: And your border shall turn from the south to the ascent of Akrabbim, and pass on to Zin: and the going forth thereof shall be from the south to Kadeshbarnea, and shall go on to Hazaraddar, and pass on to Azmon:
Contradiction with Judges 1:21
Judges 1:21 says the children of Benjamin did not drive out the Jebusites from Jerusalem, while Joshua 18:16 includes Jebus, which is Jerusalem, suggesting its inclusion in Benjamin's territory.
Judges 1:21: And the children of Benjamin did not drive out the Jebusites that inhabited Jerusalem; but the Jebusites dwell with the children of Benjamin in Jerusalem unto this day.
Contradiction with Joshua 15:8
Joshua 15:8 outlines the border of the tribe of Judah as going along the valley of the son of Hinnom, whereas Joshua 18:16 uses the same geographical marker as part of the territory for Benjamin.
Joshua 15:8: And the border went up by the valley of the son of Hinnom unto the south side of the Jebusite; the same [is] Jerusalem: and the border went up to the top of the mountain that [lieth] before the valley of Hinnom westward, which [is] at the end of the valley of the giants northward: