Max Greevey is referred to as a "sergeant." There are no detective sergeants in the NYPD. Sergeants are uniformed supervisors. A senior detective would be a "detective - first grade." All detectives are out-ranked by sergeants.
In the scene where Cragen goes to City Hall in uniform, the bagpipe band at the beginning of that scene is actually the New York City Fire Department bagpipe band, not the Police Department's.
Ben Stone: "The last time conspiracy was easy to prove was Judas and the Romans." However, the conspiracy against Jesus was between Judas and the Pharisees/Sanhedrin (the Jewish religious leadership who wanted Jesus dead).