This is just a short version based on collective works of all the other people.
Astronomy – The fact that Koran omits the movement of the earth rather talks about the sun and the moon is clear evidence that Koran was a man made book.
Biology – Adam and Eve rather than evolution is a clear cut example that the Koran is false.
Geology – Mountains do not prevent earthquake something the Koran is full of.
Zoology – Horses, Mules and asses were created by Allah to ride not mentioning how the humans breeded them from the wild.
There are plenty of crazy stuff but Jonah’s story is a clear example of all claim and no evidence.
These are my top reason as to why Islam and Koran are false and that it was a man made book.