When Ramon holds the detectives hostage in the squad room, the dangling handcuff on his left wrist constantly changes from being locked closed to hanging open.
When Ramon holds up the precinct, four detectives - including Fish - are grouped together, with Fish on the left. After the commercial break with Barney, Fish runs in from the left to join the other three.
The entire series assumes that detective police officers are first responders to crime scenes, when usually uniformed officers are.
The radio announcer at the beginning says "This is 113 on your FM dial..." The FM band does not have a 113, only 88 - 108 MHz.