* AuthorExistenceFailure:
** For Latin American viewers, this movie could be hard to watch if you know that Carl's Mexican voice actor (Tito Reséndiz) died a few months later after dubbing this movie to Spanish and 9 days before its release.
** This can also be said for the Brazilian viewers, with the death of comedy legend, Chico Anysio (the BZ actor for Carl).
** The Norwegian actor of Carl also died shortly after dubbing the film. There's a lot of death going on in and out of the film, apparently.
* CompletelyDifferentTitle: Called ''Kâru jiisan no sora-tobu ie'' ("Old Man Carl's Flying House") in Japan.
* TheDanza: Young Ellie was played by Pete Doctor's young daughter Ellie.
* {{Defictionalization}}:
** Though it lacks the balloons and has a basement, someone built a real-life copy of Carl and Ellie's house, complete with a painting over the fireplace. [[http://www.sltrib.com/sltrib/home2/52141049-183/bangerter-disney-movie-parade.html.csp In Herriman, Utah]].
** Still, a group of people actually ''did'' manage to float a house using helium-filled balloons -- appropriately enough, for a TV show called ''How Hard Can It Be?''
* DubNameChange: In the Swedish dub, Russell's name is Oskar.
* EasterEgg: On the main menu of the UK Blu-ray (and other releases), pressing the Left arrow on your remote control reveals "The Egg", a short piece in which the film makers discuss the abandoned plans to make [[spoiler:Kevin's eggs]] into the elixir of youth.
* EnforcedMethodActing: [[http://www.youtube.com/watch?feature=player_detailpage&v=iiz-j-hbCQw Used extensively for Russell's lines.]]
* InternationalCoProduction: The Latin American Spanish dub features mostly Mexican voice actors, but also includes voice actors from Argentina (Roberto Carnaghi as Muntz) and Peru (Gian Marco as Beta).
* SimilarlyNamedWorks: ''Up'' shares its name with a Music/PeterGabriel album, a Music/RightSaidFred album and a Russ Meyer film.
* ShrugOfGod: Russel's mention of a Phyllis was written to be ambiguous whether she's just his dad's secretary (meaning he's busy at work) or his father's second wife.
* TalkingToHimself: Bob Peterson voices both Dug and Alpha.
* ThrowItIn: The "That's not gonna work" gag started out as a joke ending to an early version of a scene, where Carl really ''did'' try to get Russell out of the house on a rope. They kept it.
* WhatCouldHaveBeen
** See EasterEgg above. Scrapped due to teetering into a sudden genre shift to horror.
** The original opening involved young Ellie and Carl constantly out to [[SlapSlapKiss punch each other]] due to a childish rivalry until they fall in love in their teen years. Then, one of Ellie's last acts in her hospital bed is to throw Carl an affectionate punch in the chest. Needless to say, Pete Docter said he got funny looks from test viewers.
** Initially Carl would make a balloon animal of Kevin to lure Muntz into its labyrinth home, then abandon him there. This piece of AlasPoorVillain was done away with due to Pete Docter feeling that it made the ending more about Muntz than Carl and Ellie.
** Other endings were considered, including one where [[HeelFaceTurn Muntz would redeem himself]] after talking to Carl; one where he got his foot tangled in the balloons and was pulled up into the air; and one where he ran into the house to grab what he thought was Kevin (actually just another balloon) and was followed by his dogs, their combined weight causing the house to fall.
** Kevin was originally introduced with Carl and Russell finding her in one of Muntz's traps and freeing her. Then Docter realized it wouldn't make much sense after she'd been dodging his traps for decades.
* WriteWhatYouKnow: Pete Doctor was inspired to do a film about an aggressively antisocial character based on his own social anxieties that came with being an artist.
* TropeNamer:
** ConeOfShame
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