Actually Doyle is just doing some scanning, to make sure nothing bad is going down. So he's scanning various spots, as I'm pretty sure the other soldiers are doing, trying to make sure that there are no surprises and nothing bad is happening.

EASY GOER
Regarding the scene of Doyle watching residents through his rifle night-vision scope, I have no doubt it is Don and his kids he stays focused on the longest, and what they are doing (as you mentioned). I totally agree with you about "no reason for it to happen", as it is a scene which could (and should) have been cut for the simple fact that it has no bearing at all on the plot of the film. I too, like this film but, I like "28 Days Later" more; simply because it was the first and (consequently) more original film. It is mentioned in the Trivia section Cillian Murphy, Naomie Harris and director Danny Boyle were unavailable for this film due to prior engagements. There is no question Jeremy Renner, Idris Elba and Robert Carlyle are fine actors in their own right. I personally like all of the lead actors from both films a lot, in varying degrees. In my opinion, Cillian Murphy has gone on to become a true star since the first film was made. Remember, it was released almost 15 years ago (June, 2002). Jeremy Renner is terrific and the same goes for Idris Elba; they both are very good, and have top films under their belt. Another interesting item I read in the Trivia section is the character of "Doyle" is a reference to the director of "28 Days Later", Danny Boyle. It consists of the "D" from "Danny" and the "oyle" from "Boyle" making
"Doyle"
. Lastly, I read Danny Boyle wants (or wanted?) a third film to make named "28 Months Later". However, it was said too many of the people involved (ie: writers/producers) "weren't speaking with each other"; therefore, nothing would happen until they do (start speaking with each other). Peace.

Another thing, which doesn't bug me at all, but there was no reason for it to happen:
The set-up is when we see Doyle checking out the residents through his rifle's night-scope.
One of the apartments he finds is Don and his kids. Notice Tammy is already in bed, and Andy is jumping up and down on his before Don trips him up, which makes Doyle chuckle. Nice scene. (I suppose some may argue that this is not that family and is somebody else, because we don't see them up close, but I'm pretty sure it is them).
Anyway, next we see Andy and Tammy face-to-face in the same bed, where he's commiserating about not remembering what his Mom looked like.
Just a bit of a goof.
Great movie, though.

Not sure what you're referring to with the first one??

As a screenwriter, striking a balance between documentary-realism and KISS is always there, with paramount above all being the cost to attain the best result. Consider this: How many in the audience detected the things you did, and are concerned about them? There are just as many skeptics about the film when it comes to the bio-science.
However, I do agree with you on this scene in that it strikes me as though they wanted something to look like "found footage" all of a sudden. The shaky-camera syndrome in most of the rest of the film was bad enough, as far as I'm concerned.
Still, one of my favorite films it contains the big breakout scene that we never got to see in 28 Days Later.