* ActorInspiredElement:
** Creator/DylanBaker created the Owen character himself. The snorts, facial tics, and twisted expressions are all his own making. Lulie Newcomb, who played his silent wife, said it was extremely difficult to keep a straight face while filming the scene with him.
** Both Neal Page and Del Griffith derive RealLife personality traits from the actors who play them. John Candy has the same affable, easygoing demeanor as Del. Steve Martin is a bit of a neat freak who is easily grossed out like Neal and many of his disgusted reactions are genuine.
* AwesomeDearBoy:
** Creator/SteveMartin was convinced to join the production after favoring two scenes he had read from the script; the seat adjustment-scene in the car, and the F-word tirade at the car rental desk.
** Creator/JohnCandy claimed that it wasn't one specific part of the script that convinced him to come on the project, but his opinion that all of Del's lines read like things he'd actually say and think.
* BillingDisplacement: Although he receives fourth billing, Creator/MichaelMcKean appears in only one scene, and is on-screen for ninety seconds.
* CastTheRunnerUp: Creator/SteveMartin and Creator/JohnCandy were cast in each other's roles.
* CreatorsFavoriteEpisode: Both Creator/JohnCandy and Creator/SteveMartin called their performances their favorites of their entire careers.
* DeletedRole:
** Creator/JeriRyan was cast, but her part was cut from the final release.
** Debra Lamb's role was cut from the final finished version of the film.
* DeletedScene: Watching the movie on TV gets you an extra scene where Neal struggles to eat his airplane dinner, which the Bluray had as a deleted scene. Thankfully, a 2022 4K release of the movie has over 70 minutes of deleted scenes and extended scenes from the movie, restoring a lot of the orphaned references below.
* DyeingForYourArt: John Candy got his hair permed for the role.
* FriendshipOnTheSet: Steve Martin and John Candy became close friends while making the movie and remained so until Candy's death in 1994.
* HeyItsThatPlace:
** The real life house used as Neal's house is in the same neighborhood as the house used for Kevin [=McCallister=]'s house in ''Film/HomeAlone1'', which Hughes wrote and produced.
** The rural train station, where Neal and Del buy the tickets for their ill-fated train ride, is the same station seen in ''Film/TheNatural''. It's located in South Dayton, New York.
* MethodActing: According to Lulie Newcomb, who played Owen's wife, Owen wiping spit from his face before shaking Neal's hand was unscripted. Dylan Baker (Owen) learned that Steve Martin, like Neal, was something of a neat freak, so he did that to generate an actual reaction of disgust.
* MissingTrailerScene: A scene that is not included in the movie, but featured in the trailer, shows Del in the bathroom of the first motel he and Neal are staying in. In the scene he does, among other things, an impersonation of Music/ElvisPresley in which he sings into his hair brush.
** In fact, many more scenes seen in the trailer, such as Neal eating pizza in the first motel and several lines of dialogue while they are driving their burned out car, can also be seen in the trailer.
* OrphanedReference: Due to more than half of the film's original running time being cut, a number of gags, subplots and even characters don't get their intended setup, requiring some creative editing choices to help fill in the blanks.
** The scenes on the airplane originally ran longer and gave more credence to Neal's accusation that [[TheBore Del told too many boring, irrelevant stories]]. After asking Neal about his career, Del would ramble about his own, which eventually devolves into rambling about ''Film/{{Psycho}}'', intrusive personal questions about Neal's showers and a Music/{{Prince}} biography he'd just read before Neal politely asks for some quiet. Del's response that he [[HypocriticalHumor also hates when someone else talks his ear off]] would have been more of a "HereWeGoAgain" joke as a result. The airplane food scene (the only deleted scene to be properly released) would have also served this purpose.
** The guy who breaks into Neal and Del's room and steals their cash while they're asleep was originally a pizza delivery guy getting revenge on Del and Neal after Del had given him a paltry tip of one dollar. Del would have been shown paying for the pizza with Neal's money, albeit with Neal's permission, which Neal mentions the following morning when he assumes Del robbed him. The [[NoodleIncident exploding beer can Neal mentions]] was also shown as they'd eat, as the script called it, "the ugliest pizza ever."
** There was going to be an ongoing subplot that Neal and his wife were on the verge of divorce, Neal was eyeing other women (a written but not filmed scene had Del commenting on Neil having multiple skin magazines in his luggage) and [[MistakenForCheating Neal's wife being under the assumption that "Del" was made-up and the real reason Neal hadn't come home was because he was with another woman]] - in fact, this had happened before and is why Neal rushes to take the 6:00PM flight instead of waiting for the later flight John suggests, as he knows that if he isn't home exactly at the time he promised it's all but guaranteed that Susan will believe he had another fling and they will fight about it. This is why her phone calls with Neil have an undertone of suspicion and she cries TearsOfJoy upon meeting Del and seeing that [[CassandraTruth Neal was telling the truth]].
** Why does Del have a black eye when he comes to tell Neal that he found a trucker who's willing to give him a ride home? In the final film, Del's line that the driver is uncomfortable letting people ride up front implies that [[NoodleIncident the driver punched him out of paranoia]], but in the original cut, it's Neal who gives it to him, after Neal gets strip-searched at the police station following the revelation they overshot Chicago. Turns out Del forgot to put auto insurance on the rental car that he put in Neal's name.
* PlayingAgainstType: Unlike most of John Hughes' writing and directing works during the '80s, this film focuses on adults rather than teenagers.
* TheRedStapler: There has long been fan interest in "The Canadian Mounted", the smut book that Del is seen reading at the airport. It was long believed that the book was a prop, given that it doubled as an ActorAllusion to John Candy. It is actually a real book which was published in 1981. Original copies of it are rare, as it was already out of print and in the public domain by virtue of its publisher going bankrupt by the time the film was released. Public interest in the book was rekindled when a prop recreation of it was seen in ''Film/Deadpool2'',[[note]]Which Creator/RyanReynolds specifically did as a tribute to John Candy.[[/note]] which lead to popular confirmation that it was indeed a real book. New copies of it are now available and a Canadian publisher sells a replica that contains trivia and behind-the-scenes information about the film.
* ScrewedByTheLawyers: Music/EltonJohn and lyricist Gary Osborne were commissioned to compose the theme song for the film. They had nearly completed writing it when, just two days before they were to record it, Paramount Pictures issued a last minute demand that the original song master become property of the studio. Elton's record company, Polygram, would not allow this as he was under contractual obligation to give Polygram rights to all his released music. Paramount and Polygram could not reach a deal in the impasse, both composers withdrew from the project and the song was never recorded. Paramount instead opted to license Paul Young's cover of "Every Time You Go Away" as the movie's theme song, but because Young's record company, Creator/ColumbiaRecords, wouldn't allow it, a different cover was recorded in its place (Young, a huge fan of both Steve Martin and John Candy, later said that he was quite upset about this).
* StockFootage: The shot of Neal and Del's plane in flight is taken from ''Film/{{Airplane}}''.
* TechnologyMarchesOn: If mobile phones were as common back when this movie was made as they are today, things would have been different for Neal. Or at the very least, his trip wouldn't have been as troublesome: for one thing, it would have been much easier to call or text his wife to give her regular updates on his ETA, and finding the next flight or the nearest hotel is as easy as opening an app. On the other hand, Neal seems the type who would not only run the battery on his mobile devices into the ground in order to keep working on the go but also be too impatient to stop to charge it somewhere, nor would he be resourceful enough to think of bringing a charger. Meanwhile, a traveling salesman like Del would most likely be able to afford a cheap flip phone only capable of making calls (interestingly enough, the 2010 film ''Film/DueDate'' still manages to borrow heavily from this film despite having been made in the internet age).
* ThrowItIn: A twofer for the car rental scene. It was Edie [=McClurg=]'s idea to have her character be on the phone when Neal walks up to her, just to make Neal have to wait longer. Originally she was on the phone with another customer, but John Hughes suggested that she be taking a personal call in order to [[KickTheDog twist the knife just a bit further for Neal]]. Her phone conversation seen in the film was completely ad-libbed.
* TroubledProduction: The experience of making the film was not a happy one for Creator/JohnHughes as many shooting days would either be lost or delayed due to weather issues or having to work around certain loopholes (for example, a sequence involving a train had change shooting locations due to a lack of snow and the crew had to create a train route from scratch as the local train company wouldn't allow them to use theirs). Also, the rough cut ran over three hours and the film spent many months in post-production so to cut the film to a manageable length (this is also why there are a few references to Hughes's next film, ''She's Having a Baby'', as it begun production right after this film finished filming). In addition to these problems, Hughes was also smarting over the fact that his long term business relationship with Creator/MollyRingwald had gone sour after she turned down the Creator/LeaThompson role of Amanda Jones in ''Film/SomeKindOfWonderful''. Hughes was so upset over the rejection that he never worked with Ringwald again for the rest of his life.
* WhatCouldHaveBeen:
** Creator/JohnHughes originally wanted Creator/TomHanks for the role of Neal Page and Creator/JohnTravolta for the role of Del Griffith. But Hanks was unavailable as he was busy shooting ''Film/{{Big}}'' and Paramount executives did not want Travolta, whose career had taken a considerable dip in the '80s after starring in such flops as ''Film/TwoOfAKind1983'' (this being before his CareerResurrection with ''Film/LookWhosTalking'' and ''Film/PulpFiction'').
** Creator/RickMoranis was considered for Neal Page. Had he been cast, it would have reunited him with his ''Series/{{SCTV}}'' co-star Creator/JohnCandy. Meanwhile, Creator/JohnGoodman was considered for Del Griffith. Had both Goodman and Moranis been cast, it would have presaged their casting as Fred Flintstone and Barney Rubble in ''Film/TheFlintstones''.
** The original ending was slightly different. [[spoiler:Neal would have stayed on his train and gotten off at his local station, only to find Del sitting there. Del would reveal he took a cab there specifically so he could tell Neal the truth about his wife and living situation, causing Neal to take pity on him and bring him back home for Thanksgiving dinner.]] It was decided it made Del come across as too clingy and unsympathetic, so the crew used editing and blooper footage of Steve Martin on the train [[spoiler:to have Neal realize the truth himself and go back to the downtown Chicago train station to confirm his suspicions and bring Del with him.]]
** The original screenplay also contains a subplot where Neal's marriage is suggested to be in trouble, with his wife Susan increasingly skeptical of his increasingly outlandish adventures and beginning to suspect him of having an affair, to the point where she was planning to leave him [[spoiler:before meeting Del and realising he was telling the truth]].
* WordOfGod:
** Creator/JohnHughes said in 1999 that several of his movies, including ''Film/SixteenCandles'', ''Film/TheBreakfastClub'', ''Film/FerrisBuellersDayOff'', and ''Planes, Trains And Automobiles'', are all a part of the [[TheVerse same universe]]. According to Hughes, Del lived two houses away from [[Film/TheBreakfastClub John Bender]].
** Hughes has confirmed that Del overshot Chicago during the highway night drive and the two of them were in the outskirts of Milwaukee by the time the rental car got impounded, since the footage confirming this has been cut from the final film.
* WriteWhatYouKnow: Creator/JohnHughes was inspired to write the film's story after an actual flight from New York to Chicago he was on was diverted to Wichita, Kansas, thus taking him five days to get home.
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