Continuity mistake: When Mrs. Novotny offers to get aspirin, Angie helps her up by Mrs. N.'s left hand - there's no blood on it, but the next shot shows her hand quite covered in dried blood. Mrs. N. has no blood on her clothes, despite being right next to her husband while he bled to death and Carol administered CPR.
Continuity mistake: Carol is working on James' injury and Duncan goes to answer the phone. James has his arm wrapped around the phone but the shot changes to focus on Robert - we can still see James but his arm is now at his waist, even though he had no time to change positions.
Continuity mistake: While Carol is trying to save Mr. Novotny's life, Mrs. Novotny's hair alternates from being loose and hanging over her cheeks to being neatly tucked back into her bun. In fact, a few minutes later when Carol asks for her keys, her hair looks just-brushed shiny and newly coiffed - it's unlikely she would have fussed over her hair at this stressful time.
Plot hole: Carol and Duncan escape out the back of the shop - but there are no police waiting for them, which makes no sense at all. In reality, with such a situation, the police would have been waiting at the back door. There seems to be no one around at all, as they were able to dash through an apartment. When they finally do run into a cop, he automatically assumes that Carol is an innocent bystander, and not one of the robbers. He couldn't have known this, and in reality, a policeman wouldn't assume it.