Contradiction with Numbers 13:32
Numbers 13:21 says the spies explored for 40 days, but in 13:32, the land is described as one that "eateth up the inhabitants," suggesting immediate danger rather than a lengthy exploration.
Numbers 13:32: And they brought up an evil report of the land which they had searched unto the children of Israel, saying, The land, through which we have gone to search it, [is] a land that eateth up the inhabitants thereof; and all the people that we saw in it [are] men of a great stature. [men...: Heb. men of statures]
Contradiction with Numbers 14:34
Numbers 13:21 reports the duration as 40 days, but Numbers 14:34 equates the exploration period with 40 years of wandering, creating a symbolic contradiction.
Numbers 14:34: After the number of the days in which ye searched the land, [even] forty days, each day for a year, shall ye bear your iniquities, [even] forty years, and ye shall know my breach of promise. [breach...: or, altering of my purpose]
Contradiction with Numbers 20:16
Numbers 13:21 describes the extent of the land explored by the spies, but in Numbers 20:16, the land is not mentioned as explored but only as journeyed through to reach Canaan.
Numbers 20:16: And when we cried unto the LORD, he heard our voice, and sent an angel, and hath brought us forth out of Egypt: and, behold, we [are] in Kadesh, a city in the uttermost of thy border: