* ActorAllusion: One of the fishes hums the theme to ''Film/MissionImpossibleIII''. Coincidentally, Arturo Mercado Jr. (the young Once-ler's Mexican VA) voiced Ethan Hunt in that film.
* BillingDisplacement: Trailer only. The film's opening credits are actually appropriate, starting with the three characters from the book in order of importance (Danny [=DeVito=] as the Lorax, Ed Helms as Once-Ler, and Zac Efron as Ted) and the rest following. [[NeverTrustATrailer The trailer on the other hand]] plays up Zac Efron and Taylor Swift, Ed Helms, and gives Danny [=DeVito=] an "AndStarring".
* CutSong: There are a few on the soundtrack, as well as some alternate versions of "Thneedville" and "Everybody Needs a Thneed".
* IronyAsSheIsCast: Despite Ted and Audrey being voiced by Zac Efron and Taylor Swift respectively, their characters never sing a note.
* MultipleLanguagesSameVoiceActor: Creator/DannyDeVito voiced the titular character not only in English, but also in Italian, German, Spanish (both Latin American and European), and Russian.
* TheOtherMarty: In the Mexican Spanish dub, Jesse Conde was cast as the Lorax, and he even recorded the dialogue in advance. However, Creator/DannyDeVito, the Lorax's English voice, was eventually cast to dub over Conde's lines before the release.
* ProductPlacement: Thankfully avoided in the movie itself, but some of the crossmarketing [[http://www.scpr.org/programs/madeleine-brand/2012/03/01/22732/how-mazdas-lorax-campaign-went-awry hasn't been without controversy]].
* RealLifeRelative: In the Mexican Spanish dub, Arturo Mercado voices the Once-ler, while his son Arturo Mercado Jr. plays the younger version of the Once-ler.
* UnderminedByReality: The film's numerous corporate tie-ins screw up the message quite spectacularly. The Lorax speaks for the trees, and Mazda!
** In the Mexican Spanish dub, Memo Aponte Mille was considered to voice Ted before actor and singer Alfonso Herrera was eventually selected.
** There was originally a different [[https://www.youtube.com/watch?v=BpgUQYARIsw song that served as Once-ler's villain song]] instead of How Bad Can I Be. It wouldn't have been out of place in a rock opera, and was a fair amount darker and less goofy than the final product, showing that greed and pride were the reasons Once-ler went as far as he did.
** Onceler was once going to be a non-human character. Designs ranged from [[http://ericguillon.blogspot.com/2016/06/looking-for-once-ler-early-sketches.html?m=0 things looking out of]] ''VideoGame/RaymanOrigins'' to versions resembling [[http://ericguillon.blogspot.com/2016/07/looking-for-once-ler-early-sketches.html?m=0 pre-existing Seuss characters]] like the Grinch or the guy who didn't like Green Eggs and Ham.
* WordOfGod: On the DVD commentary, it is mentioned that after "How Bad Can I Be?", 5 years have passed.