Plot hole: Megan is suspended because the police were not able to find the gun the robber had (stolen from Eugene at the scene) and believed that she had killed an unarmed man. This is very unrealistic because surely they would have interviewed all of the hostages/witnesses at the robbery and each would have easily confirmed that the robber had a gun, and possibly that Eugene might have been missing right after the incident.
Plot hole: After Meaghan's best friend was shot why wasn't the bullet matched to confirm the shooter? No way would she have not heard a gunshot 10 feet away in the bathroom of her apartment even with towel around it. No rookie would be given a temporary detective badge after a shooting.