After re-watching the scene in which Julian is shot (the scene in which there are no cuts, only one continuos shot), I came across an an interesting interview  of Cuaron. In the interview, he explains how the scene came down to the last possible take and that the blood splatter on the camera was actually an accident. What I find amazing is that with so many opportunities for a mistake to ruin the take, in the end it actually helped out the scene and made it more visually entertaining.  http://io9.com/this-iconic-scene-from-children-of-men-was-actually-an-840211730