Dennis Franz (Detective Andy Sipowicz) is the only actor to appear in all two hundred sixty-one episodes. Gordon Clapp (Detective Greg Medavoy) holds the number two spot, appearing in two hundred fifty-six episodes.
The man we see playing the violin just before the closing credits of this show (and most other Steven Bochco productions) is Bochco's father. They computer animated a portrait of him to make it appear he's playing the violin.
According to Steven Bochco, Sherry Stringfield asked the producers to release her from her contract after the first season because she said she was not enjoying being a television actress and wanted to return to New York City. Less than a week after being let out of the contract, she was hired as a regular cast member for the new television series ER (1994). However, in his book "True Blue", David Milch said that Sherry's contract-end request came about because she had very little to do, the prominence of Andy Sipowicz's relationship with Sylvia Costas, took all of the story time that was originally intended for scenes between David Caruso and Sherry, and the request was amiably granted, with Milch also stating he was happy when she got a prominent role on ER (1994).
Prior to the show's premiere, and immediately afterward, there was enormous controversy over what was perceived to be high levels of offensive language and nudity. Many affiliates refused to air the show and several advertisers boycotted it. Steven Bochco negotiated intensely with the network for a certain amount of language and nudity to be allowed. He has said that because of the pressure on the network from this criticism, the show would likely not have survived, had it not been an instant hit.
The sets on this show of the "New York streets" were on the backlot of Twentieth Century Fox, and were originally built for Hello, Dolly! (1969). Some location work was actually done in New York City for most of the show's run, mixing specific scenes with general location footage that was used for between-scenes and opening-credits sequences. During the final seasons, however, the combination of high costs for location filming and the show's reduced ratings meant that one hundred percent of filming was done in Los Angeles.
Before joining the cast as Detective Connie McDowell, Charlotte Ross appeared in the fifth season as the abused wife of a cop suspected by Detective Bobby Simone (Jimmy Smits) and Detective Diane Russell (Kim Delaney) of killing a prostitute. When Andrea Thompson left the series, Producer Steven Bochco remembered Ross, and wrote the part of McDowell for her.
Jimmy Smits left the show once his initial contract ended. During the show's run, he found the constant last-minute re-writes frustrating and chose not to extend it, but stayed on for a five-episode arc at the beginning of season six to allow his character have an explained departure.