Contradiction with Genesis 6:3
This verse states that the days of man shall be 120 years, contradicting the long lifespans, like the 905 years lived by Enos, in Genesis 5:9.
Genesis 6:3: And the LORD said, My spirit shall not always strive with man, for that he also [is] flesh: yet his days shall be an hundred and twenty years.
Contradiction with Genesis 5:32
This verse records Noah having three sons at age 500, which seems unattainable with the shortened lifespan suggested by Genesis 6:3.
Genesis 5:32: And Noah was five hundred years old: and Noah begat Shem, Ham, and Japheth.