Continuity mistake: Toward The End of the episode when the older mobster is walking from his car down a narrow alleyway toward home, he passes under a low hanging outdoor light fixture. When he is accosted by the other mobster with a gun they are standing with the light fixture between them. There is no movement, but when the police arrive, the light fixture is well behind the guy with the gun.
Factual error: The badge the ATF Special Agent is displaying on his suit jacket is wrong. It's the wrong shape and style of an actual ATF Badge. (00:02:57)
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.