Embassy Combat Scene a Joke
We see Marines running around, making themselves easy targets and being shot, then running around some more still in a fashion that made them easy targets, being shot up more. Meanwhile they never return fire, never attempt to ID the whereabouts of the snipers firing on them. The Marines in the movie firefight generally act like arcade game targets.
If there was a Col. Terry L. Childers, he should have been court martialled for incompetence on this point alone. But then, in another bit of implausibility, we see a full colonel where we would more likely see a 2nd lieutenant or even a non-com in command.
And we are further asked to believe that this situation would even arise. The embassy would have its own Marines, would have control of its own external security and not be entirely dependent on the Yemeni government. A quick, organised surprise attack could overwhelm things outside the embassy temporarily, but not for hours on end. Embassy security should have been able to handle the crowds and snipers the movie shows after an initial attack. And the movie shows no evidence they even tried this.
And the Yemeni government withdrawing their troops? Embassies are located in capital cities. If a government can't control their own capital city, they can't be a government. Maybe they withdraw troops in the case of a full out civil war. But in doing so, they violate their own sovereignty and then invite the U.S. to do the same. Wouldn't happen.