[em2vn]

Some questions for you. Does the shooter seem to stand out in sharp relief to those around him and is the casing being ejected to the front of the weapon? What should be the relation of the smoke exiting the barrel to the ejected brass if only one shot as been fired?
The taller man should be doing a very rapid hot brass dance if the photo is real and more than one shot has been fired.

[JamesP81]

Does the shooter seem to stand out in sharp relief to those around him and is the casing being ejected to the front of the weapon?

I kind of thought so, but I'm no photographic expert, so it's hard for me to comment on standing out in sharp relief. However, it looks to me like the ejected case is in front of the ejection port on the rifle. I've fired a couple of M4s / M16s and it seems to me that all of them kicked the brass back and to the right of the shooter. I suppose perspective could be deceptive here, but it sure looks fishy to me.

What should be the relation of the smoke exiting the barrel to the ejected brass if only one shot as been fired?

Hard to say. I've never seen geniune slow motion film of it, so I'm not sure.