* AllStarCast: Virtually every major comedic actor from the early 1960s stars, and everyone from Creator/JerryLewis to Film/TheThreeStooges makes an appearance. Over five minutes of opening credits detail a parade of celebrity appearances.
* BillingDisplacement: Creator/SpencerTracy gets top billing and doesn't appear until nearly twenty minutes into the film.
* CastTheRunnerUp:
** Creator/JackBenny was originally tabbed to play Captain Culpeper. After Creator/SpencerTracy got the part instead, Benny wound up having an uncredited cameo.
** Creator/PhilSilvers was originally suggested for another one of the main roles.
** In a bit of clever casting Creator/BusterKeaton was originally supposed to have played [[IronicNickname Smiler Grogan]], while Creator/JimmyDurante was to have portrayed [[TheDanza Jimmy the Crook]]. The roles were later switched.
** The roles of Melville and Monica Crump were originally larger roles written for Creator/MickeyRooney and Creator/JudyGarland. When production of ''The Judy Garland Show'' ran into trouble, Garland had to turn down the part. Rooney eventually got the role of Ding "Dingy" Bell. Edie Adams, who was originally cast as Emeline, got the role of Monica.
* TheDanza: Eddie Rosson as Eddie, the miner's son.
* {{Defictionalization}}: The area where Grogan "sailed right out there" on California State Route 74 is now known as Smiler's Point, a sought-after location for fans.
** As is the location where the "Big W" was located, Santa Rosita State Park. All that is left of the palm trees in question are some stumps in the ground.
* DeletedRole:
** Among the deleted scenes in Culpeper's office were a series of telephone conversations with a "Dr. Chadwick" and an "Uncle Mike." The roles were respectively played by Elliott Reid and Morey Amsterdam.
** Another deleted scene featured Creator/DonKnotts trying to get to a diner telephone, which was being used by a waitress played by ''Series/GreenAcres''' Barbara Pepper.
** Yet another deleted scene featured Ding and Benjy helping a showgirl (Eve Bruce) with some suntan lotion.
** A dance sequence featuring Music/TheShirelles was filmed but never used. However, their uncredited performances of the title song and "31 Flavors" stayed on the soundtrack.
** Cliff Norton and King Donovan respectively played a detective and an airport official that appear at the Rancho Conejo airport. Neither role made it into the finished film. Strangely, Norton's name remained in the opening credits.
* EditedForSyndication: Around 31 minutes of footage were cut from the film following its premiere screening, bringing it down from 3 hours and 12 minutes to 2 hours and 41 minutes. Most of this cut footage was restored for the VHS and Criterion Collection DVD releases, with the latter featuring some extra footage from the 3.5 hour original cut.
* EnsembleDarkHorse: Creator/PeterFalk as the irritable cab driver is one of the most popular and memorable characters in the film, even though he doesn't appear until just before the climax of the film. He practically becomes a main character by the finish.
* FakeShemp: Legendary Hollywood stuntman Carey Loftin, who was also the stunt supervisor for the movie, was Smiler Grogan's foot when he kicks the bucket.
* FatalMethodActing: Thankfully averted. Creator/PhilSilvers, while filming the scene where Meyer drives his car into the river, nearly drowned because he couldn't swim.
* FollowTheLeader: This movie's success led to such other epic-scale, all-star race comedies as ''Film/TheGreatRace'' and ''Film/ThoseMagnificentMenInTheirFlyingMachines'' over the next couple of years.
* HarpoDoesSomethingFunny: Creator/PeterFalk improvised much of his dialog in the cab scene.
* MissingEpisode: The footage of several of the scenes that were cut between the premiere and the general release has been lost, to the point that even the Criterion Collection version (which includes footage that was cut ''before'' the premiere) is five minutes short, and four scenes only exist as audio over production stills. These include Mrs. Marcus spotting Ding and Benjy while attempting to flag them down as they pass her and the others, Mrs. Melville first getting the idea to use the blow torch on the hardware store basement door, Sylvester's girlfriend trying to stop him from driving off in her husband's car, and Culpeper having a phone conversation with Jimmy the Crook (Creator/BusterKeaton) to make the arrangements to flee to Mexico by boat.
* MoneyDearBoy: Creator/EdieAdams almost didn't accept the role of Monica because her husband Creator/ErnieKovacs had been killed in an auto accident a few months earlier. However, she did accept because Kovacs had died deeply in debt and Adams had vowed to pay off all of her husband's creditors – a pledge she fulfilled by accepting this and all other roles she was offered after his death.
* PlayingAgainstType:
** Creator/StanleyKramer was a director best known for dramas regarding social issues (''Literature/OnTheBeach'', ''Theatre/InheritTheWind'', ''Film/JudgmentAtNuremberg'', etc.). Although admittedly the film, on top of being a superb slapstick comedy, is a very effective social satire on greed. Also, many of the cast members were primarily known for being stand-up comedians or sitcom actors as opposed to "pratfall" comics.
** There were also minor straight roles played by comic actors: Creator/NormanFell is one of the cops who interrogates them in the beginning, Andy Devine and Creator/StanFreberg are the sheriff and his deputy Culpeper is on the phone with early in the movie, Creator/CarlReiner and Jesse White are the air traffic controllers, [=ZaSu=] Pitts is the switchboard operator, Joe E. Brown is the man giving a speech at the end, and Ben Blue is the pilot with the ancient plane.
** Both Creator/PeterFalk (the cab driver) and Creator/SterlingHolloway (the fire chief) became iconic for their mellow comic roles, while here their characters get realistically hoarse and surly with the antics of the treasure hunters.
** Averted with Creator/SpencerTracy, who plays the role of Capt. Culpepper more or less completely straight.
* PromotedFanboy: Of a sort — Creator/PeterFalk said that he had long been a fan of Eddie "Rochester" Anderson, and was overjoyed to work alongside him in this film.
* StillbornFranchise: During the 1970s, Creator/StanleyKramer considered reuniting much of the film's cast for a proposed movie titled ''The Sheiks of Araby''. ''It's a Funny, Funny World'', a sequel of sorts, was also proposed. There was supposedly a sequel that was proposed in TheEighties called ''It's a Mad, Mad, Mad, Mad, MAD world". (After a gag that Kramer wanted to add a "Fifth mad")
* ThoseTwoActors: {{Subverted}}. The film features several pairs of actors known for working together who ironically share no scenes – among them, Creator/JackBenny and Eddie "Rochester" Anderson, Creator/PhilSilvers and Paul Ford, Creator/SidCaesar and Creator/CarlReiner, Alan Carney and Wally Brown, Leo Gorcey and Stanley Clements, and Creator/BusterKeaton and Creator/JimmyDurante.
** Played straight with Creator/ArnoldStang and Marvin Kaplan, who'd previously voiced Top Cat and Choo-Choo respectively on ''WesternAnimation/TopCat''.
* WagTheDirector: Creator/SidCaesar got into a screaming battle with writer William Rose about re-writing his lines. Creator/StanleyKramer defused the situation by bringing out Creator/SpencerTracy and introducing him to the comic.
* WhatCouldHaveBeen:
** Several performers were considered for roles in early planning stages, or filmed scenes that were ultimately cut. They include:
*** Creator/JackieGleason as one of the main players.
*** Creator/LucilleBall as one of the main players' female companions.
*** Creator/MaeWest as Mrs. Marcus.
*** Creator/PeterSellers as Algernon Hawthorne. Sellers wanted too much money, leading Stanley Kramer to hire the next best thing (Creator/TerryThomas).
*** Creator/BobHope was to have had a cameo, but was refused by the studio he was under contract to at the time.
*** Creator/GrouchoMarx was originally written in as a doctor that would have appeared at the end of the film to deliver the final punchline. The role was written out, but Groucho was offered a cameo role. He ultimately never appeared in the film. In a letter to a fan, Groucho jokingly said that he was to have played the Ethel Merman role.
*** Creator/JackBenny's cameo role was originally offered to [[Creator/LaurelAndHardy Stan Laurel]], but he turned it down, not wanting to work without Oliver Hardy, who'd died in 1957. A long shot of the character had already been filmed with a stand-in wearing Laurel's trademark bowler hat, which is why Benny is seen wearing a bowler hat despite having never worn one in his other work.
*** Creator/HaroldLloyd was offered the role of the Santa Rosita mayor, but declined, as he was happily retired by this point.
*** Despite Creator/DonRickles' later joking about the fact that he never appeared in the film, Stanley Kramer once claimed that Rickles was offered a role but had to turn it down because of scheduling conflicts.
*** Creator/JudyHolliday was offered a role, but declined due to ill health.
*** Edie Adams' husband Creator/ErnieKovacs was originally cast as Melville, but was killed in a car crash before shooting began. Creator/SidCaesar replaced him.
*** Creator/DonaldOConnor was considered for Benjy Benjamin.
*** Creator/EdWynn was originally supposed to play the Fire Chief, having starred in the ''Texaco Fire Chief'' radio program in the early 1930s.
*** Others offered roles included [[Creator/AbbottAndCostello Bud Abbott]] and Creator/GeorgeBurns.
** The original script was about a comedic chase through UsefulNotes/{{Scotland}} and was envisioned as a fairly small-scale British comedy akin to the many that William Rose wrote during his years in England.
** According to Nicholas Georgiade, he was to have another scene in which his character had a police radio conversation with Captain Culppeper. The scene was ultimately not filmed.
* WorkingTitle: The film was originally titled ''Where, But in America?'', was then later changed to ''One Damn Thing After Another'', then finally became ''It's a Mad World'', with Creator/StanleyKramer and writer William Rose adding additional "Mad"s to the title as time progressed. (Kramer considered adding a fifth "Mad" before deciding that would be too much, and later said he regretted not doing so.) Other proposed titles included ''So Many Thieves'' and ''Something a Little Less Serious''.
* WrittenInInfirmity: Creator/ArnoldStang broke his left forearm just days before his scenes were shot. In all shots he wears a garage workman's gloves on both hands and his left arm is always crooked, and held in place by a cast concealed under his garage uniform.

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