Cast the Runner-Up: Gary Busey was supposed to play Tom, but quit before filming began. Keith Carradine, who was originally cast as Bill, took over the role. Even though he left, one of the songs Busey wrote for the movie ("Since You've Gone") stayed.
The Cast Showoff: Of the actors who portrayed singers, only Ronee Blakley and Allan Nicholls had been professional musicians prior to the movie, but the others had all either played music on the side, did musical theater, or in the case of Karen Black and Timothy Brown, had worked as nightclub singers alongside their acting.
Henry Gibson reportedly stayed in character as Haven during the whole shoot, to the extent that his wife was getting worried about him.
Allan Nicholls was so into playing Bill that he was genuinely shocked and hurt when he saw the dailies of Tom and Mary in bed togethernote he hadn't read the whole script, even though he was close friends with Keith Carradine and Cristina Raines in real life.
Keith Carradine was disgusted by Tom, but realized that it was helping his performance since Tom was a character who thoroughly hated himself.
Barbara Harris disappeared from the set several times without explanation, leading some people to suspect she was staying in character as Winifred/Albuquerque full-time.
The argument between Barnett and Triplette at the Parthenon was improvised. Michael Murphy was so startled at how vicious Allen Garfield was getting that he screwed up one of Triplette's lines ("you're putting the knife in her back, bu-buster!") but it stayed in the film.
The Elliott Gould and Julie Christie cameos happened because they both came to Nashville to visit the set and Altman decided to put them in the film.
The role of Linnea Reese was created for and by Louise Fletcher, who herself was the daughter of two deaf parents and knew sign language. The role was eventually played by Lily Tomlin, who concluded that things worked out in the end because she was offered the role of Nurse Ratched in One Flew Over the Cuckoo's Nest and turned it down, which enabled Fletcher to eventually get it, so in a sense they simply traded roles.
Robert Duvall was originally offered the role of Haven Hamilton but had a scheduling conflict and was unable to do so. As a result, he was replaced by Henry Gibson. In commenting on the movie, Altman has said that the movie would certainly have been different with Duvall in the role, but he was happy with Gibson playing the part.
In the UK the first two seasons aired on Channel 4 diginet More4, with season three being on sister channel E4. As it didn't quite fit on the channel (among its series are Hollyoaks, Empire, Baby Daddy and endless airings of The Big Bang Theory) along with the long delay in airing season three, the series moved to Sky Living for season four.
In the US, however, it did this when CMT picked it up for a fifth season post-cancellation.
Contractual Purity: Juliette dislikes how her fanbase are almost entirely teenage girls and how she is restricted to performing with sparkle machines and dancers. When she tries to perform a more mature and low-key song at a concert, alongside the others, a critic smashes her, but her fans like it.
Also applies, in a sense, to many of the characters played by actual Americans with only Will Chase (from Kentucky) coming from anywhere close to Tennessee (Alabama native Juliette is played by New York State-born Hayden Panettiere, while Teddy Conrad is played by fellow New Yorker (he was born in Staten Island) Eric Close).
I Knew It!: Many people guessed that Micah was Jason's son and not Gunnar's as soon as Kiley mentioned him in her debut episode.
Name's the Same: There was a show on FOX in 2007 also called Nashville. It was a reality show that taped only six episodes, four of which never aired.
It's also totally unrelated to the Robert Altman film (although at least one British journalist, writing in The Times, seems to think it's a remake).
Similarly, Avery's song "The Most Beautiful Girl In The World" is not a cover of the Charlie Rich track.
No-Hit Wonder: Deacon. Outside of Nashville, he's unheard of. But literally every musician in the show loves his music; even Liam, the rock musician who hates country, claims to be a fan of his. Within the music industry, there is an arms race between three artists/bands to get him on their tour.
The songs released from the series itself. Those that have charted on the country charts did so almost entirely from downloads, with almost no support from radio. The only exception is Hayden Panettiere's "Telescope", which barely hit the Top 40 on the airplay chart.
Non-Singing Voice: Averted - all of the actors do their own singing (as demonstrated in the Nashville: On The Record specials and on tours).
Scully Box: For some reason the show's promotional shoots try really hard to hide how much shorter Hayden Panettiere is than nearly all the other cast members (even though the show itself almost never does - see Throw It In! below for instance).
Troubled Production: Implied by T-Bone Burnett in an interview with The Hollywood Reporter after he left the show (which he had always intended to do after the first season):
Some people were making a drama about real musicians' lives, and some were making a soap opera, so there was that confusion. It was a knockdown, bloody, drag-out fight, every episode. You remember that show The Prisoner? If I were to tell you the truth, you'd think I was insane.
Wag the Director: The pixie haircut Scarlett debuts in "Can't Get Used To Losing You" was done with the blessings of Callie Khouri, due to Clare Bowen having suffered from cancer as a child and wishing to demonstrate that not having oceans of hair on your head didn't mean you were worthless.
Jack Coleman auditioned for a role, but the producers had already cast Hayden Panettiere and they didn't want audiences to be reminded of their previous association on Heroes. But they didn't know (or perhaps they did) that another cast member (Burgess Jenkins) had already worked with Miss Panettiere more than ten years previously in Remember the Titans...
Juliette was originally meant to be The Rival to Rayna, all the way to being the official antagonist.
Averted with Maisy Stella breaking her foot; wasn't included in the show (and given her character Daphne has yet to get her own storyline plus Maisy being the biggest Absentee Actor on set, it likely won't cause many problems).