The first inaccurate move I can see is the careless 10...Be7? which allows the typical stroke 11.Bxe6! after which Black should have a very difficult game. Maybe 10...h6 is best, since 10...Qb6 allows 11.a4 b4 12.Nd5!? and the desirable 10... Nc5 (to swap of the dangerous bishop) can be answered by 11.Bd5!, when Black has to be very careful. In general, it's safer for Black not putting the bishop on b7 that early, as it weakens the e6 soft spot.

11...0-0 still alows the same trick, but now things are far from clear.

I think it's completely clear that one should not touch such sharp+complex openings as the Najdorf without proper knowledge of the standard tactical patterns.