The show was originally about a divorced woman. Divorce was still a hot subject in 1970, so it changed to a broken engagement. The network was afraid people would think that Mary Tyler Moore had divorced Rob Petrie, her character's husband on The Dick Van Dyke Show (1961).
In the opening credits, the two joggers who pass Mary in the park are producers James L. Brooks and Allan Burns. The gray-haired man Mary has lunch with and is later takes an evening walk with is Mary Tyler Moore's then-husband Grant Tinker, president and co-founder of MTM. The woman who scowls at Mary as she tosses her hat is local resident Hazel Frederick.
According to a 2013 interview with Valerie Harper and Cloris Leachman on the TV show "The Doctors," this show was the first (scripted) show in TV history ever to use the word "gay" to refer to homosexuality (in the season three episode "My Brother's Keeper") when Rhoda tells Phyllis that Phyllis's brother is gay.
When the famous opening credit sequence was reworked for Season 3-4, the Mary crew was being followed by a news team for the talk show program "Moore on Sunday". Both the news crew and the police officer escorting the Mary team were pressed into service for one of the clips (when the Mary Richards character has to duck to avoid being caught on film as the "news" cameraman swings his camera around in the direction the officer points).
Moore wore a wig for the first season of the show, to make her look less like Laura Petrie, her character on The Dick Van Dyke Show (1961). When the wig was discarded, the change in her hairstyle, including her much lighter hair color, was never commented on in the show itself.
The photo of Edward Asner playing football on Lou Grant's office wall is the same photo that was used in an episode of The Fugitive (1963) ('Three Cheers for Little Boy Blue') in which Asner guest starred.
In the opening credits, the shot of Mary Tyler Moore throwing her hat into the air was shot at the corner of 7th Street and Nicollet Mall in downtown Minneapolis. The buildings in the background were destroyed November 25, 1982, by a fire that took out a city block. Many scenes in the opening credits, including riding an escalator and window shopping, were shot within a one-block radius of the spot. In May 2002, TV Land erected a statue of her at that spot, facing the opposite direction.
When Woody Allen was putting the final touches on his Academy Award winning film "Annie Hall", he asked his co-star Diane Keaton for reassurance: "Are you sure this is good? I mean it seems like another episode of The Mary Tyler Moore Show".
Ted Knight and Ed Asner were actually very close during the show, not enemies like their characters. Although they did get into a nasty argument after the show wrapped; Ed says Ted wronged him in some egregious manner, he just can't remember what it was. But they didn't speak for years until Ted was stricken with cancer in 1985 and they reconciled at his deathbed.
Gavin McLeod and Cloris Leachman were actually enemies in real life, much like their characters. In a case of life imitating art, they had worked together before and had a very bad experience, and Cloris was actually uncomfortable with Gavin for the first couple seasons, and didn't want to be near him on the set. Eventually they grew to be friends, though.
Robert Moore (no relation to Mary Tyler Moore) who appeared as Ben, Phyllis' brother in the "Her Brother's Keeper" episode, and who also dated Rhoda/Valerie Harper in that episode, would go on to direct Valerie in "Rhoda", the spinoff of MTM. Moore was the subject of Rhoda's famous "He's gay!" punchline, the first time it had ever been said on television. Moore didn't mind because he is gay in real life.
All the men in the cast would star in their own show after MTM wrapped, and they were all hits. Gavin McLeod headlined in "The Love Boat" the same year MTM wrapped, and it was a top 30 show for several years, probably the most popular follow up show of the bunch. Ed Asner starred in the MTM spinoff "Lou Grant" which was in the top 30 for several years. And Ted Knight starred in "Too Close for Comfort" which was also popular for a couple years.
Ted was originally supposed to be Mary's love interest. Originally they were thinking of Lyle Waggoner for the role. Then Ted Knight, an older man in his 40s, nailed the audition, and at that point, because he was older, and an innapropriate match for Mary, they jettisoned that subplot. They were also thinking of making Lou Mary's ongoing love interest, but Mary Tyler Moore herself vetoed that idea, so they had the characters date and then the romance quickly ended. Murray on the other hand was based on a gay person, someone who was supposed to be Mary's nemesis, and Gavin McLeod played him gay in the pilot; but Mary and him had such chemistry they made the characters friends, and that Mary would be the object of his crush.
Producers almost didn't hire Valerie Harper because although her performance was spot on, she was too pretty (not really convincing as Mary's frumpy best friend). They decided to dress her in ungainly and frumpy clothing and give her the part anyway.
Mary Tyler Moore said this about "That Girl" (1966), the groundbreaking feminist girl power sitcom that preceded " The Mary Tyler Moore Show": "Anne Marie opened the door and Mary Richards walked right through it".
In the 70s while the show was in production the MTM writers were invited to a panel on feminism which was moderated by Gloria Steinem. James L. Brooks attended the panel, and was surprised when Gloria Steinem publicly chided Brooks for how Mary always called her boss 'Mr. Grant' while her male colleagues called him Lou.
MTM writer and producer Allan Burns would direct Mary Tyler Moore in the unsuccessful 1986 dramedy about infidelity "Just Between Friends", co-starring two other iconic tv stars, Ted Danson and Christine Lahti.
In an EmmyTvLegends interview Nanette Fabray, who played Mary's mother, expressed great disappointment at only appearing on 2 shows, and then not being asked back after that. She was hoping and kind of assuming she would be promoted to a series regular, and she even confronted Mary about it at one point. She did go on to star as the Mom in another CBS comedy about a woman making it on her own: One Day At a Time.
John Amos appeared as Gordy the Weatherman on MTM until about 1974, when he left to go star on Good Times. In the 1976-1977 season he got fired, at which point he made another appearance as Gordy, the national network's new hero coming back.
Ed Asner won the "Best Supporting Actor for a Comedy Series" Emmy Award for his portrayal of Lou Grant on "The Mary Tyler Moore Show". He also won the "Best Lead Actor for a Drama Series" for playing the title role in "Lou Grant". Asner is the only actor who has won both of those awards for playing the same character.
In the episode where Mary got her tonsils removed originally she was going to have a tattoo removed. But the actress refused saying she was a "good catholic girl" and she "couldn't play that", so they changed it to a tonsillectomy.