When Lynette is arguing with Carolyn and Carolyn is about to shoot her, the blood on Lynette's face and position of hair above her left ear, changes between shots.
When Carolyn comes to supermarket she tells to Harvey that "he should be with Monique" and she aims her gun towards him and starts shooting. Later we see that Lynette and Nora were standing behind Carolyn when Carolyn came to supermarket in an attempt to kill Harvey. The argument between Lynette and Nora was interrupted by a gunshot fired by Carolyn but their argument lasted far more longer than Carolyn needed time to start shooting.