Kathryn Erbe's real-life pregnancy was incorporated into the show's plot line, by having her character be a surrogate mother, carrying her sister's child.
To add a vulnerability to Goren's seeming invincibility, a backstory was added in which his mother was diagnosed as a schizophrenic during his adolescence.
This is the only New York City-based Law & Order series in which Sam Waterston (Jack McCoy) did not appear.
At the end of the fourth season, Jamey Sheridan suffered Bell's Palsy, a facial paralysis that affected one half of his face. In the fifth season, his character, Captain James Deakins, wore an eye patch over his left eye to help camouflage the signs of paralysis. The effects are still visible to the discerning eye, even with the patch. The reason was never given on the show. Comments by other characters were made about the new eyewear, but the Captain was always evasive about the cause.