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)

Blue Bloods (2010)
1 factual error in season 8 - chronological order
Starring: Tom Selleck, Bridget Moynahan, Donnie Wahlberg, Len Cariou, Will Estes

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)
Frank Reagan: And I don't have a Teflon suit. Everything gets to me. Every time one of ours is hurt, or jammed up, or he's in over his head, it gets to me. I just don't show it, 'cause I can't show it, 'cause nobody wants, or needs, a sensitive police commissioner.
Sid Gormley: OK.
Frank Reagan: So screw you!
Sid Gormley: Yes, sir. That an order, too?
Frank Reagan: Yeah, that's an order.
Sid Gormley: Screw me. I'm on it, boss.
Trivia: Although Len Cariou plays Tom Selleck's father, he's only five years older than Selleck.
Question: What is the significance of the lapel pin worn by detectives on Blue Bloods?
Answer: It is an NYPD Detective Bureau lapel pin. If you zoom in on a pic of "Danny Reagan," you will see that the pin has the letters DB on it.





Answer: It is the lapel pin worn by members of the NYPD Honor Legion.
The lapel pin is on Danny but not Biaz, why? Also, Baker, Sid, Frank &Garrett wear one. Significance? Are they all the same?
Is the P.C.'s pin different than a legion pin? What are the symbols and their meaning?
I think it may be Masonic?
But why would the mayor wear one?