Goof (factual errors): Several police cars have forward facing blue lights. NYPD does not use forward facing blue lights on any emergency vehicle, and state law prohibits blue lights facing forward on police vehicles.
Goof (factual errors): For the NYPD, the Police Commissioner has the rank insignia of Five Gold stars.
Goof (factual errors): Most of the police cars used in Blue Bloods are replicas, bearing the obvious wrong font for the 'NYPD' lettering on the side, having blue lights and bearing the modified NYPD logo that's also worn on the replica uniforms. But in several episodes you can see the replica cars mixed with real-life NYPD police cars. Most of the time the precinct number on the real-life cars are not shown, since the NYPD doesn't allow real-life precinct numbers being used in TV shows.
Goof (revealing mistake): The patches on the police officer's clothing are incorrect, as they read "NEW YORK" instead of "CITY OF NEW YORK".
Goof (factual errors): The girl that was abducted was said to have diabetes type 1 and in need of insulin shots ONCE every 24 hours. This is a very unlikely treatment today, it was used in the early 1970s before research showed that more frequent injections of insulin in smaller doses dramatically improves the balancing of blood glucose levels.
Goof (factual errors): Insulin shock is a colloquial term for low blood glucose level and is very dangerous but it will not be caused by missing an insulin injection. Insulin shock can occur if you get too much insulin in relation to how much carbs you eat.
Goof (continuity error): When Danny & King are at the abduction site, there is a shot of them talking and King's tie is blowing far over his shoulder. In the next shot, it is perfectly placed back where it should be. The time frame between both shots is so short that there is no way King could have fixed his tie.
Goof (factual errors): Snorting Potassium Chloride in the amounts shown would not be anywhere near fatal.
Goof (continuity error): When Commissioner Frank is talking with Detective Melissa Baker alone in his office, her hands are first linked together behind her then in front of her then behind again, repeatedly between shots.
Goof (continuity error): When Erin and Frank are in the restaurant, Erin stops eating at one point while still holding her fork and knife in her hands. Then the camera cuts to another angle. Her hands are now empty and her arms crossed in front of her on the table, and she picks her fork and knife up again.
Goof (revealing mistake): When the character of Milli collapses, Linda checks her breathing and while her head is down by her face, Milli blinks.
Goof (factual errors): Danny asks Malevsky if the Dodge Challenger has a Hemi, and he says it does. The car depicted is a base model that does not have the Hemi (there is no R/T or SRT emblem on the front). Also, the horn sound when Malevsky disarms the alarm is not from a Challenger.
Goof (continuity error): Danny's white shirt when they get to the ER is covered in blood. In the following scenes, there is noticeably less blood on it.
Goof (errors made by characters, possibly deliberate errors by the filmmakers): The Mayor thanks Melissa Baker by her real name "Abigail" when entering the P.C.'s office.
Goof (factual errors): Erin mentions that she is an Assistant District Attorney for New York City. Each borough (or county) in New York City has its own District Attorney. Erin happens to work for the New York County (Manhattan) District Attorney.
Goof (continuity error): The circulated picture of Diane was supposedly a picture she took of herself but in it she is holding - and looking into - the camera that she is using to take a picture of herself.
Goof (errors made by characters, possibly deliberate errors by the filmmakers): When Nikki tells Diane that her uncle knows someone in TARU, she calls it the Tactical Assistance Response Unit. The "T" in TARU stands for "Technical."
Goof (errors made by characters, possibly deliberate errors by the filmmakers): "MCMXXVIII" is the roman number for 1928, not 1978 like Danny says.
Goof (continuity error): Stone brings Det. Reagan a report saying the drugs are from Guadalajara and that means it can't be Otto because his come from Durango. Later they twice refer to Devlin's shipment as coming from Durango, not Guadalajara.
Goof (factual errors): After the bookie's safe was cut open with a torch, none of the money inside is damaged. Torching open a safe will damage or destroy anything inside that is even remotely flammable.
Goof (factual errors): The inside view shown when the officer removes the safe door shows the locking bolts retracted, meaning the safe wasn't locked.
Goof (revealing mistake): During the standoff between Dylan and the police, you can see that the muzzle of Dylan's gun does not have an opening, indicating that the gun is a prop.
Goof (continuity error): As Erin is approaching Col. Seabrook, the camera view is from his back and he lifts his glass to drink. As we see her view, he has his glass near his lap.
Goof (continuity error): In the fight scene Danny has a bloody mouth before he was hit, then when his face is pushed against the mirror after the camera angle changes he is several feet away from the mirror.
Goof (continuity error): In one clip of the soapbox derby, the three cars are in reverse order, left to right.
Goof (continuity error): When Jamie and his father at chatting in the park, it is raining when we're looking at the chief but not when they cut to Jamie.
Goof (errors made by characters, possibly deliberate errors by the filmmakers): Towards the end of the show,Jamie and his partner arrest the man accused of sexual assault in a restaurant and handcuff him. They never read him his rights.