Visible crew/equipment: Towards The End of the episode as ADA Reagan is walking to her car, you can see the cones in the DAR end of the street the filming crews used for traffic control to keep traffic off the set. (00:02:30)
Character mistake: Commissioner Frank Reagan refers to Lt. Gormley as Sgt. Gormley in this episode. (00:08:30)
Continuity mistake: As Danny and Jaime are at the range shooting near the middle of the episode, their targets from behind and the grouping of shots they take are really tight together. When they retrieve their targets a minute later, the grouping from the front is completely different and further apart than what was seen from behind the target.
Character mistake: Throughout the episode they refer to the victim owning a "cement" company. In fact it was a concrete company. Although the terms cement and concrete often are used interchangeably, cement is actually an ingredient of concrete. Concrete is basically a mixture of aggregates and paste. The aggregates are sand and gravel or crushed stone; the paste is water and portland cement. (00:00:05 - 00:35:50)
Continuity mistake: One second Frank Reagan throws his glasses on his desk, the next after a brief cutaway, they are on his face. (00:36:10)
Continuity mistake: Henry sets down the pencil he was using on the crossword. In the next shot, as he is picking up his glass, it is in between his fingers. It shows him taking it from his hand with the other, but again in the next shot, is back on the crossword. (00:40:30)
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.
Visible crew/equipment: At the start of the episode, the first character (Cole) has an audio wire sticking out the back of his suit. It disappears in the next shot. (00:00:25)
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)
Other mistake: Eddie and her partner respond to a store selling sandwiches with contradicting prices. For example, grilled cheese is listed for $3.99 and $6.25, and tuna melt is $5.50 and $5.99, and BLT is listed twice on the same sign. (00:03:10)
Other mistake: Jamie and Eddie respond to a carjacking of a minivan. They are across the street and Eddie claims there's a baby seat in the car. There's no possible way that she could see if a baby seat was in the car. The minivan had dark tinted windows and only the driver's door was open. (00:05:00)
Character mistake: Officer Rachel Witten tells Eddie the gun she has belonged to her dad when he was on The Job. In episode 15 of season 8 Gormley tells Frank that Witten's dad was a FDNY Battalion Chief and her uncles were police officers. In episode 12 of season 9 Officer Witten's dad Sgt. Scott Witten speaks to Frank about being on The Job. It's unlikely and not normal for someone to become a firefighter after being a police officer or vice versa or do both jobs.
Continuity mistake: Danny and Linda are hugging after Danny tells the boys to go pay your respects to the WWII Memorial. In the next shot they are standing apart as when he told them to go pay their respects to the memorial. (00:54:34)
Other mistake: Throughout the episode, all the interactions with the characters went from day to night except for Commissioner Reagan chaperoning his grandson's class at the museum. It stayed daylight the whole time at the museum. (00:27:14)
Other mistake: Jamie races to the patrol car after witnessing a car jacking with possible child inside. He flings the door open, gets halfway inside, and the car starts without him even being close to turning the key in the ignition. (00:04:00)
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.