The Danza: Joey Lawrence played Joey in the episode "Big Brother".
Dueling Shows: ABC's Webster [1983-89], starring Emmanuel Lewis as the Gary Coleman equivalent. It even had its own Channel Hop to syndication for its final two years.
Edited for Syndication: The broadcast syndication versions of Diff'rent Strokes (which are also the versions seen on Antenna TV 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 ( 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 ( 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).
Life Imitates Art: In "Blue Collar Drummond", Mr. Drummond pretends to be an employee at his own company in order to listen to his employees' concerns and get ideas on how to make the company a better place. Over twenty years later, this became the premise for the reality show Undercover Boss.
The Other Darrin: 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 Designing Women. Similarly, in the two-part "Hooray For Hollywood," which has Arnold and Dudley sneak onto the Knight Rider set, KITT is voiced by someone who is not William Daniels. David Hasselhoffdoes appear, however.
Real-Life Relative: 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".
Recycled Script: It's been pointed out that a number of episodes have the same premise as episodes of The Brady Bunch. Most notably the ones where Arnold pretends to be dying to meet Muhammad Ali (Bobby pretended to be dying to meet Joe Namath) and Kimberly's hair turns green (Greg's hair turned orange).