If you understood it right, its an error by the translator. Its not an error in the Qur'an. Come on people! that was your best shot? I mean thats not even an argument to be discussed upon.
Subhanallah...these failed desperate attempts by the non-muslims is a proof that they have nothing to say about the Glorious Qur'an..so they come up with stupid qestions and try to proove themselves right. It's good at least you know now that the Qur'an does not have a dot worth of error in it - nor in its scripture - nor in its true meaning and wisdom.
if you say you are truthful then produce your proof.