Friends in High Places - S10-E8
Factual error: Police Officer Troy was taken into a room by Sgt Regan to be interviewed. He has one Sgt stripe on one sleeve. He's a police officer, not a Sgt.
Factual error: Danny shoots Frank's revolver, and as he continues to shoot, you hear the sound of a casing hitting the floor, which shouldn't happen since it's a revolver being fired. (00:11:46)
Fog of War - S10-E14
Factual error: During the funeral towards The End of the episode, both Jamie and Eddie are wearing white shirts with their dress uniforms. In the NYPD, only Lieutenant and above wear white shirts, like the show has portrayed. The color doesn't change for the dress uniform. (00:38:35 - 00:41:14)
Factual error: At The End of the episode, Mayor Poole is on TV discussing the recent police shooting. He refers to officer Meeks as a shooting death. Officer Meeks was wounded in the neck with spine injuries and retired medically.
Dedication - S1-E15
Factual error: When the ambulance pulls up to the hospital after Frank is shot, it is a Chicago Fire Department ambulance, not New York. (00:02:10)
Officer Down - S1-E4
Factual error: Danny and Jackie Curatola are with ESU to make an arrest at a garage. They are behind cover with their weapons drawn. Although there is no suspect shooting at them, both Danny and Jackie have their fingers on the trigger, which is against police training unless you are going to engage a subject by shooting your weapon. The ESU officer right next to them does not have his finger on the trigger. (00:38:04)
Answer: It's a common cop show plot device. If the police on the show always acted in the most logical way (i.e. not alerting a suspect to their presence) the show wouldn't have the opportunity for an exciting foot chase.