* AllStarCast
* HeyItsThatVoice: [[HighSchoolMusical Troy Bolton]], hoping to fulfill his crush TaylorSwift's dream of seeing a real tree, goes to see [[TheHangover Stu]] who got into a fight with [[Disney/{{Hercules}} Philoctetes]] over said trees.
** [[GroundhogDay Ned Ryerson]] is the Onceler's Uncle!
** In the Japanese version, MamoruMiyano and Creator/KoichiYamadera are Ted and O'Hare respectively. The Lorax is voiced by the Japanese comedian Ken Shimura.
*** So Miyano got to voice Zac Efron's role after Zac failed to get [[Manga/DeathNote one of Miyano's biggest roles?]]
** In the 1972 special, Bob Holt ([[ChallengeOfTheGoBots Cop-Tur]], [[WesternAnimation/TheGreatGrapeApe Grape Ape]], [[WesternAnimation/{{Wizards}} Avatar]]) was [[ActingForTwo both]] [[TalkingToHimself The Lorax and Once-ler]].
* IronyAsSheIsCast: Despite Ted and Audrey being voiced by the star of the ''HighSchoolMusical'' movies and TaylorSwift respectively, their characters never sing a note.
* WordOfGod: On the DVD commentary, it is mentioned that after How Bad Can I Be?, 5 years have passed.