Starting at 38:15 into the movie, when Scott shoots the officer escorting the prisoners, you can see a car in the background heading towards the scene. In the next scene, when Scott stands in the middle of the road looking for cars, the car is not present.
During the beach house scene, Scott puts the gun in his left hand (behind his back) when he speaks to the #1 man that just entered the house. He then shots him twice with the gun, but it in his right hand.
In the bar scene, when the newscast plays, Scott and another soldier talk about Scott's knife as he uses it to cut an apple. He lifts the apple to his mouth, and immediately on a reverse shot, we see the knife at his mouth as he bites a piece of apple.
When Scott tosses the straw dummy to throw off the Sniper in the boat it lands with brown shoes on - when the scene cuts to him sitting behind the boat house he has on brown shoes and the dummy has on black ones.
During the staged robbery shootings, the guy dressed as a cop drops the fuel nozzle on the ground. After he has been "shot" and Agent Scott has searched his person, Scott gets into the vehicle next to the gas pump, but the fuel nozzle is no longer on the ground.
When the red pickup pulls into the parking lot, we cut to a shot through the windshield of the driver getting out. The fuzzy dice hanging from the mirror have already stopped swinging and are hanging motionless.
The scope on Curtis's gun is an Aimpoint Comp M series. It does not magnify the image as the movie indicates, nor does it have cross-hairs. Instead, it projects a red dot in the scope showing where the bullet will hit.
The gun used by Curtis to give Scott sniper cover at the seaside cabin is a Heckler & Koch MP-5. A submachine-gun meant for close-quarter combat. It is neither designed for, nor is ever used as, a sniper rifle. Its ammunition wouldn't even fly straight if shot through a window.