Contradiction with Numbers 21:24
Numbers 21:30 mentions Israel's conquest and destruction of Heshbon down to Dibon, while Numbers 21:24 speaks of Israel smiting Sihon with the edge of the sword and only possessing his land.
Numbers 21:24: And Israel smote him with the edge of the sword, and possessed his land from Arnon unto Jabbok, even unto the children of Ammon: for the border of the children of Ammon [was] strong.
Contradiction with Deuteronomy 2:19
Numbers 21:30 recounts taking different territories, but Deuteronomy 2:19 instructs Israel not to disturb the Moabites or seize their land.
Deuteronomy 2:19: And [when] thou comest nigh over against the children of Ammon, distress them not, nor meddle with them: for I will not give thee of the land of the children of Ammon [any] possession; because I have given it unto the children of Lot [for] a possession.
Contradiction with Joshua 13:9
Joshua 13:9 describes the extent of the land of Gilead which was distributed, contradicting the complete destruction suggested in Numbers 21:30.
Joshua 13:9: From Aroer, that [is] upon the bank of the river Arnon, and the city that [is] in the midst of the river, and all the plain of Medeba unto Dibon;