When the sniper first looks through his scope at Smitty and Steffan on the roof Smitty is to his six o'clock position and Steffan is at twelve o'clock position, After Smitty's phone rings he moves 90 degrees to the Sniper's nine o'clock and Steffan turns putting him at three o'clock yet when the sniper looks through his scope Smitty and Steffan are still in their original positions.
In the opening rooftop assassination scene the corner of one of the snow covered tables is pristine; then disturbed: then pristine; then disturbed.
When Reese is pursuing Simpson, the objective lens cap on his scope varies between open and closed as the scene cuts from one shot to another.
In Greece the guys is looking at a German newspaper, which has spelling mistakes on it. For example "toetet" will be written "tötet" in German and "zentrum" suppose to be "Zentrum".
At the start, the sniper tells the female spotter to Range Me and she pick up a wide speed indicator and uses that to give him the distances instead of a rangefinder.
During the opening credits there are several short clips of the sniper meticulously making his own custom hand-loaded ammunition. In one if the clips during the reloading process there are a few grains of gunpowder that are spilled while filling the brass case. Any real marksman would know that even a few grains of gunpowder would make a huge difference on extreme long range shot placement.
In a number of scenes, one or more of the team are seen entering a building or vehicle with their sniper rifle ready, extended to engage, when they have side arms. Sniper rifles are long weapons and can be grabbed easily from around a doorway or wall.