Continuity mistake: On the speedboat at the end of the movie when Archer and Troy fly through the air, you can see foam on their clothes even though in the next scene their clothes are dry. (02:02:25)
Continuity mistake: At the church, just as the shooting is done with, Eve is leaning down with her hands covering her head. Then, in the close-up she uncovers her head and sits upright to look around, but in the next shot, she's still leaning down covering her head. (01:54:30)
Continuity mistake: In the scene where Cage and Travolta are fighting on the dock, Cage stabs Travolta with the speargun (before he fires it). If you look at the spear after Travolta is stabbed, there is blood on it. Then in the next shot, the spear is suddenly clean.
Continuity mistake: When John Travolta is shot on the carousel at the beginning of the movie, the shot enters his back near his collarbone. When the camera moves back a second later, the bullethole is much lower.
Continuity mistake: At their home, when Sean tells Eve that he has one last assignment we see his scar. At the Walsh Institute, before the surgery, there is another close-up of the scar, but it differs from the previous shot. (00:30:20 - 00:33:05)
Continuity mistake: When John Travolta's daughter slams her bedroom door in his face, from one shot it nearly closes, but in another shot he blocks it when it's still got a long way to go. (00:54:35)
Continuity mistake: In the shoot-out sequence in the Mexican Standoff scene between Archer, Castor, Sasha, Eve, and Castor's two bodyguards, you don't need to look carefully to see that the exact same footage is used twice at different times to show a flowerpot exploding. Also, a bad guy gets shot and falls the exact same way twice at different times. He doesn't even fall at a different camera or body angle.
Continuity mistake: When Castor Troy first arrives at the airplane you see another business jet in the back (you see the red engine coverages). Few seconds later there is a different aircraft with a propeller and no jet anymore.
Continuity mistake: When Troy (as Archer) arrives home for the first time, he's walking around his wife. When he says her name, his right hand is held up. From a different angle as he moves to her right, his hands are by his side. (00:52:50)
Continuity mistake: Towards the end of the boat chase, the "Coast Guard" boat is facing towards the two boats. A few seconds later one of the chase boats flies through the Coast Guard boat from its rear. It would have taken too much time to spin that boat around for the boat to crash through the back. And even if it were possible, most of the crew were shot and fell off the boat. Who drove the boat to position it for the crash?
Continuity mistake: Castor Troy puts three bullet holes in the windscreen of the helicopter Sean Archer is in at the start of the movie. When Archer moves toward the hangar to shoot Castor, you can see in the background that there are now no holes.
Chosen answer: Although they were on the same side, Troy is currently posing as Archer, which means he would have to do everything that the FBI would expect Archer to be doing. The whole point of the raid was to take out Archer, as well as Troy's gang. He would have rather risked killing part of his own gang than risk exposing his identity to anyone else.
Casual Person
That doesn't really make sense. In the scene, he goes out of his way to shoot him and smiles while doing so, carefully and slowly. Was not a collateral damage situation. The question is why he deliberately goes out of his way to kill him.