Contradiction with Jeremiah 42:10
Jeremiah 42:10 indicates that God promised to build and not pull down the people if they stayed in the land, which contradicts Jeremiah 43:7 where they disobey God's command and go to Egypt.
Jeremiah 42:10: If ye will still abide in this land, then will I build you, and not pull [you] down, and I will plant you, and not pluck [you] up: for I repent me of the evil that I have done unto you.
Contradiction with Jeremiah 42:19
Jeremiah 42:19 explicitly warns the people not to go to Egypt, which they disobey in Jeremiah 43:7, thus contradicting the instruction given.
Jeremiah 42:19: The LORD hath said concerning you, O ye remnant of Judah; Go ye not into Egypt: know certainly that I have admonished you this day. [admonished...: Heb. testified against you]
Contradiction with Jeremiah 44:12
Jeremiah 44:12 predicts disaster for those who went to Egypt, whereas Jeremiah 43:7 depicts their actual journey to Egypt, defying God's warning.
Jeremiah 44:12: And I will take the remnant of Judah, that have set their faces to go into the land of Egypt to sojourn there, and they shall all be consumed, [and] fall in the land of Egypt; they shall [even] be consumed by the sword [and] by the famine: they shall die, from the least even unto the greatest, by the sword and by the famine: and they shall be an execration, [and] an astonishment, and a curse, and a reproach.