* AbsenteeActor: Averted by Conrad Bain, who is the only cast member to appear in every episode.
* ActorAllusion: Whitman Mayo plays a junk dealer in "The Adoption"; he previously played the friend of a junk dealer on ''Series/SanfordAndSon''.
* TheCastShowoff: Dana Plato was a trained figure skater, which the producers allowed her to demonstrate in "Family on Ice" (with SpecialGuest Dorothy Hamill).
** Music/JanetJackson's singing was featured in the episode "The Music Man".
* ChannelHop: To [=ABC=] for the final season.
* TheDanza: Joey Lawrence played Joey in the episode "Big Brother".
* DuelingShows: [=ABC=]'s ''Series/{{Webster}}'' [1983-89], starring Emmanuel Lewis as the Gary Coleman equivalent. It even had its own ChannelHop to syndication for its final two years.
* EditedForSyndication: The broadcast syndication versions of ''Diff'rent Strokes'' (which are also the versions seen on Creator/AntennaTV since 2013) feature fairly noticeable (and to some extent, poor) edits for time constraints: the most glaring are the season three episode "The Older Man", in which both a scene dissolve and a wipe take place at almost the same time while transitioning to a scene in which a 25-year-old man who is dating Kimberly ([[spoiler: due to her being mistaken for a 20-year-old, while dressed in makeup and costume for a school play]]) arrives at the penthouse to take Kimberly out on their date; the episode "The Athlete" from the same season, features a brief clip of a scene in which Willis teaches Kimberly a dance move, which then abruptly switches only ''two'' seconds later to the scene in which Willis gets his acceptance letter to Fillmore High ([[spoiler: as promised to him by that school's shady baseball coach, who uses his sister's address to get most of his recruits accepted into the school]]).
* FollowTheLeader: ''Series/{{Webster}}''.
* TheOtherDarrin: Mary Ann Mobley replaced Dixie Carter as Maggie [=McKinney=], the woman who marries Mr. Drummond in the show's seventh season, when Carter left to play Julia Sugarbaker on ''Series/DesigningWomen''. Similarly, in the two-part "Hooray For Hollywood," which has Arnold and Dudley sneak onto the ''Series/KnightRider'' set, [=KITT=] is voiced by someone who is not William Daniels. Creator/DavidHasselhoff [[TheCameo does appear]], however.
* RealLifeRelative: Betty Bridges (Todd Bridges' mother) played the voice of Arnold and Willis' mother on an audio tape in "Memories". She also played the mother of one of Willis' friends in "Willis' Birthday".
* YouLookFamiliar:
** Rosalind Chao played Arnold's teacher Miss Chung, as well as the character Ming Li in the episode "Almost American".
** Before playing Maggie Drummond in Season 8, Mary Ann Mobley played Arnold's teacher in "Teacher's Pet".
** Jack Riley played four different characters on the show (three of them during the show's first season).
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