The Bible insists that Noah's flood was global and no one survived except the believers who boarded the Ark with Noah. However the Quran says that the flood was local and all nations other than Noah's survived.
Local floods are very common however there is no scientific evidence for a global flood. But stories of a global flood are found in many ancient cultures all-around the globe. If it were a global flood, as portrayed in the Bible, no one would have survived other than the believers who boarded the Ark with Noah. There would be no disbelievers who didn't board the Ark and survived. However the Quran says something else. It says that there were disbelievers who didn't board the Ark but still survived:
[Quran 11:48] It was said, "O Noah, disembark with peace from Us; and with blessings upon you, and upon communities from those with you. And other communities We will grant prosperity and later We will hand them painful torture."
In the Quran other people survived. Since God will punish them later then definitely they were disbelievers who were not onboard the Ark. If only believers boarded the Ark but still disbelievers survived then this means that it was just a local flood. Those who were not in the area survived.
The very next verse says that this story was not known before:
[Quran 11:49] These are some stories from the past that we reveal to you. Neither you, nor your people knew them before this. So be patient. The future belongs to the pious.
The Bible insists on a global flood killing all disbelievers. The story in the Quran, that other disbelievers survived, was not known to previous cultures. The Quran was the first to proclaim it.
In the Quran the last prophet was sent to all nations however Noah was sent to just his own people:
[Quran 21:107] We did not send you except as mercy to all nations.
Alameen لِلْعَالَمِينَ in Arabic means "all nations". The last prophet was sent to all nations. However Noah was not sent to all nations but sent to just his own people:
[Quran 7:59] We sent Noah to his people. He said, "O my people! Worship Allah; you have no god other than Him. I fear for you the punishment of a tremendous Day."
In the Quran Noah was sent to just his own people, not to all nations. And those who were drowned by the flood were disbelievers from his own people, not from all nations.
The Quran never said that God drowned all nations Alameen الْعَالَمِينَ. However the Quran consistently said that God drowned only the people of Noah:
[Quran 25:37] And the people of Noah: when they rejected the messengers, We drowned them, and made them a lesson for mankind. We have prepared for the wrongdoers a painful retribution.
God drowned disbelievers from Noah's own people قَوْمَ نُوحٍ and made them a lesson for mankind. The Quran never said that God drowned mankind.
Noah was sent to just his own people, not to all nations. And Noah presented God's revelations to just his own people, not to all nations. And those who rejected the revelations were from Noah's own people, not all nations. So God drowned disbelievers from Noah's own people, not all nations. In the Quran all other nations had nothing to do with the flood. This means that it was just a local flood.
There is no scientific evidence for a global flood however local floods are very common. No mistakes in the Quran.
How could an illiterate man who lived 1400 years ago have known that there was no global flood?