The Uniform - S2-E11
Character mistake: While handcuffing an auxiliary officer in his apartment, there is a poster on the wall reading, "attention military personal..." Personal is misused. It should read "attention military personnel." (00:16:02)
Character mistake: Sergeant Gormley is promoted to Lieutenant in the previous episode. In this episode he is referred to as Sergeant Gormley by Commissioner Reagan and Deputy Commissioner Garrett Moore at least twice.
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.
Dedication - S1-E15
Continuity mistake: At the start, Frank isn't wearing glasses at the table. Then in one shot he is. Then not again. (00:00:40)
Continuity mistake: During the stakeout of the apartment building, in the exterior shots of the Clyde Motorcycles shop, Danny is peeking out through a ripped paper opening within the letter "D" in Clyde. However, in the interior shots the black tape letters of the word Clyde differs. The paper is ripped between the two letters "D" and "E" and that space within the "D" is blocked with molding, making what is in the exterior shots quite impossible. (00:15:40)
Visible crew/equipment: As Danny gets out of the car, with the bad guy who shot Erin in the courtroom, holding her hostage and coming out to meet him behind the courthouse, as Danny gets out of the car, in the driver's side car door mirror you can see a crew member in a red shirt holding one of those "scene marker" slap boards. (00:32:40)
Continuity mistake: At The End of the episode, a screen shot of Nicki occurs. A day or so earlier, she had been kidnapped and pistol whipped across the face. But this screen shot shows no bruises or swelling or anything, despite being hit so hard she fell over in a chair just a day or so before. (00:40:00)
Nightmares - S3-E7
Visible crew/equipment: While Jaime talks to Malcolm on the street and takes his picture it's being filmed from two camera angles. When Malcolm shoves Jaime and he falls to the ground we can see the second camera's tripod leg at the right side of the screen, and as Jaime gets up we can see the second camera as well.
Revealing mistake: A runway model drops dead. Linda runs over and checks her. The model blinks, and Linda announces she is dead. (00:06:20)
Nightmares - S3-E7
Continuity mistake: In the very first episode Frank Reagan is getting dressed to go to Jamie's graduation ceremony. He slips on his watch and then takes a ring with a blue stone (looks sort of like a class ring) and puts it on. It is definitely and obviously a large blue stone. Then in this episode, near The End, when Frank is sitting at the bar talking to Garrett, as Frank lifts his drink in his right hand, and Garrett says "Thank you, Frank", that "class ring" has a very definite and obviously large red stone. (00:01:20 - 00:40:50)
Continuity mistake: Near The End of the episode, just after Danny's family is looking at the Statue of Liberty, Danny puts his arm around Linda, and then does it a second time.
The City That Never Sleeps - S4-E2
Continuity mistake: Danny and his partner are driving with a passenger in the back seat. You can see both front seat headrests removed while they are talking in the car. Next shot shows the car from outside and you can see the headrests are on the seats.
Character mistake: In this episode, Garrett says that "Nom de Guere" means pen name. It means war name. Nom de Plume means pen name and Garrett is supposed to be an expert in his field.
Continuity mistake: Jamie's car is suddenly yellow when offering driving lessons. In previous episodes, the car is blue. (00:40:18 - 00:41:16)
Visible crew/equipment: After Baez tells Danny that detectives from Moscow are on their way to help with the investigation, when it cuts to Anthony entering the courtroom, just as Erin removes her glasses the T-mark is visible on the floor behind her, at the bottom left side of the screen. (00:08:35)
Visible crew/equipment: After the opening credits, when it cuts to Frank's office a red tape mark is visible on the floor near the window, at the right side of the screen. After Nicky leaves the office it appears Frank walks to that area to look out of the window. (00:04:35)
In and Out - S7-E14
Continuity mistake: At the start, the rearview mirror on the windshield of Eddie and Jamie's squad car disappears and reappears.
Character mistake: When Henry and Jamie are putting away leftovers from dinner, Jamie puts food in a plastic container and then puts the dirty fish in the cabinet with the clean dishes.
Audio problem: While at the range, Jamie takes Frank's revolver to the line and fires it. The last 2 shots you can hear the casings hitting the ground, but not on the first 3 shots. The last 2 shots are from another camera angle. Revolvers don't eject the casings, so we shouldn't hear them landing.
On the Arm - S12-E11
Character mistake: Lt. Gormley mentions a Captain (Captain Terrell) taking items On the Arm that is a 33-year veteran. Captain Terrell tells the PC that when she was 12 her brother was wounded in Iraq. If she has 33 years on The Job, there's no way she could have been 12 during the war in Iraq. The Vietnam War would have been more appropriate for the age and background of Captain Terrell. (00:00:21 - 00:14:33)
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.