Based on the series-ending twist, the show is the center of what is known as the "Tommy Westphall Universe". The show had a crossover with Cheers (1982), and several characters were featured in Homicide: Life on the Street (1993). From those links, the program can be linked to at least 280 other non-animated shows, ranging from I Love Lucy (1951) to CSI: NY (2004) (as of 2007).
One episode called for Dr. and Mrs. Craig to visit Philadelphia. Inspired by returning to Independence Square, William Daniels sang a few lines of the song, "Sit Down, John!", from 1776 (1972). (The line was "It's hot as hell in Philadelphia!") The moment was included in the episode. (He also mentioned that there was something about being in the city of Philadelphia that just made him want to sing and dance). Daniels played John Adams in that movie. In this episode Dr. Craig (Daniels) also mentions to his wife that back in medical school he was "obnoxious and disliked" which is also something said by John Adams to his wife in "1776".
The show was known for its inside jokes. The writers named characters after series staff members, they wrote lines that referenced other TV shows, movies, plays and books. One had to be up on current events and the arts to understand some of the humor.
The elevated train seen in the opening titles is the Orange Line of the Massachusetts Bay Transportation Authority, Boston's public transportation system. During the final season, the Orange Line was moved to an underground route and no longer ran on elevated tracks, thus making its appearance anachronistic.
Friends and family members of the cast and crew often provided the names of the doctors paged over the PA system. If you listen closely during several episodes, you can hear a page for Dr. Gwyneth Paltrow. Her father, Bruce Paltrow, was the series' executive producer.
In one episode, Dr. Axelrod and P.A. Luther Hawkins are trying to cheer up Dr. Fiscus, who had been shot. Among the things they perform to do that is blowing up rubber surgical gloves, then putting them over their heads, to no avail, prompting Axelrod (Stephen Furst) to make a comment about the guy on TV who got a big laugh on TV doing the bit - which was Howie Mandel, who played Dr. Fiscus.
The writers of this show shared a building and a copy machine at MTM with the writers from Hill Street Blues (1981). Whenever they needed inspiration, they would look at a script from "Hill St." and that always pushed them to do better.
The orderly, Warren 'Cool' Coolidge, was also a character played by the same actor in The White Shadow (1978). In one episode we see him wearing his Carver High School varsity letter. In another episode, when an actor from "Shadow" played a different role, that actor was mistakenly referred to by his name from "Shadow". The actor corrected the "mistake" on camera.
The show was sued by Humana because of similarities between the company and "Ecumena", the company that took over St. Eligius in the show. The show eventually dropped the name and issued a disclaimer on each episode.
The last episode is full of inside jokes, including a doctor named Brandon Falsey, a reference to Brand and Falsey, the creators of the show. There was a chase of a "one armed man" a reference to the Fugitive. During the chase, someone yells, "Move the gurney, Hal," a reference to Hal Gurnee, Dave Letterman's director.
Actor William Daniels said that when he was offered the part of Dr. Craig, he was not only given the pilot script to read, he was given the first three scripts to read. He said producers did this to show that his character was prominent in some episodes but not others. Daniels said it gave him a sense of the ensemble nature of the show.
At the memorial service for Dr. Caldwell ('Mark Harmon'), who died of AIDS, Nurse Rosenthal commented that Caldwell always thought he was the sexiest man alive, which was a reference to Mark Harmon being named People Magazine's Sexiest Man Alive in 1986.
Just like ER - St. Elsewhere does a 5 minute straight shot scene with a single moving camera where cast members jumps in & out doing their lines & if someone screws up (especially the last group) the whole thing is to be re-done again - from the start.