The Stage Plays
- What Could Have Been: Originally the debut stage production of the female version of the play was going to star Nancy Walker and Joan Rivers, and be directed by Neil Simon himself. It ended up starring Rita Moreno (who was replaced with Brenda Vaccaro later in the Broadway run) and Sally Struthers, with Gene Saks directing the production.
The 1968 Film
- AFI's 100 Years… 100 Laughs: Ranked at #17.
- What Could Have Been:
- Art Carney (who played Felix on Broadway) wasn't seen as very marketable by Paramount, so Frank Sinatra, Dick Van Dyke and Tony Randall, among others, were considered for the movie role before settling on Jack Lemmon. Jackie Gleason, Mickey Rooney and Jack Klugman were among those considered for Oscar before Walter Matthau was called to reprise his role.
- Walter Matthau asked director Gene Saks if he could instead play Felix, as he wanted an acting challenge after perfecting the role of Oscar in the original play. Saks flatly refused.
The 1970- 75 Series
- Acting for Two: Tony Randall occasionally would also play Felix's relatives, such as his father in a flashback, and his grandfather in an episode where Grandpa Unger is thrown out by his wife and moves in with Oscar while Felix is out of town on business.
- Actor Allusion:
- In "Cleanliness is Next to Impossible," Oscar actually wants to change his slovenly ways because they bother his girlfriend, so Felix attempts to help him out with psychology by bringing in a hypnotist friend played by Allan Arbus, better known as army shrink Sidney Freedman on M*A*S*H.
- One of the origin stories about the guys' friendship has Felix as a Rogue Juror, with Oscar having to room with him when he forces a sequester. Jack Klugman had starred in the classic film of this trope, 12 Angry Men.
- Actor-Inspired Element:
- The TV show featured a greatly increased focus on Oscar's gambling, especially at the track, and Felix's love of opera because those were particular interests of their respective actors.
- Oscar's wardrobe on the show was, in many cases, Klugman's own.
- Edited for Syndication: When Klugman and Randall complained about the laughtrack during the first season, ABC aired a trial episode without one (the episode in which Oscar gets fired from the paper and takes a job with a girly magazine). While initially syndicated without a track, one has been edited in in recent years.
- Executive Meddling:
- Mainly focused around eliminating any hint, much less outright reference, to homosexuality. This is why the "Can two divorced men share an apartment without driving each other crazy?" spiel was added to the opening credits; it also resulted in one script being tossed out completely and the end of another ("The Flying Felix") being heavily rewritten.
- Like it happened to The Brady Bunch, ABC's standards at the time still forbade as late as 1971 that divorced characters could have children. Oscar (who had two sons in the play and movie) became explicitly childless, while Felix's kids began appearing in the second season.
- In the third season the network decided that what the show needed were guest stars. The show almost became a Lucy-like star-of-the-week clone, with everyone from Howard Cosell to Bob Hope to Bobby Riggs to Rodney Allen Rippy taking their turn at bat.
- Harpo Does Something Funny: Some scripts were like this, allowing Tony Randall and Jack Klugman to improvise. For example, a script might say "Oscar teaches Felix how to play football."
- Prop Recycling: The 'black donut' painting from the second season episode "Security Arms" shows up again in season three's "Take My Furnature, Please".
- Real-Life Relative:
- Husband and wife Jack Klugman and Brett Somers playing a divorced couple. In real life, Klugman and Somers split up during the series and she still came back to guest star, meaning they were a separated couple playing a divorced couple.
- Klugman's son Adam appeared as "Little Oscar" in a few episodes.
- In her final episode as Myrna, Penny Marshall's real life brother (Odd Couple producer Garry Marshall) and sister appear as her character's relatives, and her then-husband Rob Reiner played Sheldn, Myrna's boyfriend.
- Recycled: The Series: From a play to a movie to a TV series. Many prefer the series to the film.
- Recycled Set: The first season was shot on the same apartment set as the film.
- Throw It In!: The scenes of Felix and Oscar out in the streets of New York during the intro were completely improvised. One of the show's directors simply followed Randal and Klugman around New York and filmed them doing various things in-character.
- Trolling Creator: Randall and Klugman would intentionally play up the homoerotic subtext on certain takes and the producers would put those into the initial cuts sent to the network censors because they knew it would cause studio executives' heads to explode.
- Un-Cancelled: The show had decent ratings through its inaugural season, but later plummeted, to the point it was cancelled in 1972, 1973 and 1974, only to be renewed by summer reruns, which got higher audiences than in their first runs. During the summer months, Klugman and Randall would do a tour of the original play to hype up the series, encouraging viewers to write in and request that the show remain on-air.
- Vindicated by Reruns: The show kept shifting timeslots while on the air, so only during summer reruns, when it was on at a consistent time, did it gain a significant audience. When the series finally ended and went into syndication, it got those consistent timeslots once again. Its popularity skyrocketed (just as Klugman himself had confidently predicted).
- What Could Have Been:
- Art Carney and Dean Martin (!) were both considered for Felix. Mickey Rooney and Martin Balsam were both considered for Oscar.
- For the second season, the network gave the producers two options: include the narration during the opening title, "Can two divorced men share an apartment without driving each other crazy?", or add lyrics to the theme song that basically proclaimed Have I Mentioned I Am Heterosexual Today?.
- There was an alternate finale filmed that would have aired in the event that the show was picked up for a sixth season.
- Written-In Infirmity: Klugman and Randall took on the roles again in a series of late '80s/early '90s commercials for Eagle brand potato chips, all of which had to be written around Klugman's nearly non-existent voice after his heavy smoking resulted in him losing a vocal cord. Later came 1993's The Odd Couple: Together Again, by which time Klugman had regained some volume, but still spoke in an extremely raspy and wheezy voice, so Oscar is said to have recently had the same throat operation.
- You Look Familiar:
- In one episode Alan Arbus (best known as Dr. Sidney Freeman) plays a hypnotist, in another a Hollywood director.
- Comedian John Bynner plays a parking lot owner in one episode and a weight-loss pill company exec in another.
- John Fiedler played a dog trainer in one episode and the owner of an ultra-secure security building in another, as well as playing Vinnie in the movie and Felix in some Broadway productions.
- Richard Stahl appeared in nine different episodes as nine different characters. Among them are a monk, a minister, and a pet shop owner.
The New Odd Couple
The 2015 Series
- Actor Allusion: When Oscar (Matthew Perry) is talking about marriage with Charlotte, he mentions leaving an Oscar-shaped hole in the door. When Matthew Perry was on Friends, his character, Chandler, mentioned leaving a Chandler-shaped hole in the door.
- Actor-Shared Background: Thomas Lennon is a cellist. He is actually playing the instrument live whenever Felix is playing on the show.
- The Character Died with Him: Oscar's father (played by Garry Marshall) was killed off following Marshall's death.
- In Memoriam: The season three episode "Taffy Days" served as one of these to Garry Marshall, who had played Oscar's father Walter and served as creative consultant on this iteration (and developed the 1970-75 series). The stars of Marshall's other series Happy Days, Laverne & Shirley and Mork & Mindy all made guest appearances, and the episode was dedicated to his memory (with a clip of the original series' theme song, as well as pictures of Marshall with the 1970s and 2010s Couple leads, playing alongside the dedication).
- Real Life Writes the Plot: The writers weren't sure if the show would last beyond a single season and decided to compress Felix and Emily's Will They or Won't They? plot and brought about a definite conclusion so that the audience would at least get some sense of closure in the event of a cancellation.