Here is a post that takes a look at the textual reliability, scientific reliability, prophetic accuracy and historical accuracy.

Excerpt:

While the list of historical inaccuracies and anachronisms is vast, one has been selected for discussion here. Surah 20 relays the incident of the golden calf. In Surah 20:85-88, 95 we read:

“He [Allah] said, ‘We have tempted thy people since thou didist leave them. The Samaratin has led them into error.’ Then Moses returned…and we cast them [(gold) ornaments], as the Samaritan also threw them, into the fire.’ (Then he brought out for them a Calf, a mere body that lowed; and they said, ‘This is your god, and the god of Moses, whom he has forgotten.’)…Moses said, ‘And thou, Samaritan, what was thy business?’”

Now, let us consider this for just a moment. How can a Samaritan have led the Israelites astray at the time of Moses (approx 1400 BC) when the city of Samaria was founded by King Omri in about 870 B.C? The Samaritans did not exist until after the exile of the Northern kingdom of Israel and the resettlement of the area under king Sargon II in 722 B.C. with non-Israelites who then adopt a syncretism [mixture] between the religion of the Jews and their own polytheistic background. The Samaritans did not exist until 530 years after Moses. By this mistake alone, the Qur’an can be rendered unreliable and certainly not an inerrant work of God.

This is important, because Muslims think that the Qu’ran is without error.