Executive Meddling: Subverted. It's assumed that the decrease of the women's bust size in Knick-Knack is Disney executive censorship as usual, but John Lasseter and the studio actually made the decision to do so themselves.
Parodied in Your Friend the Rat, which ends with a prolonged legalistic crawl warning people that Pixar does not encourage people to have contact with rats. Remy and Emile bitch about the inclusion of this producer-imposed warning (which is Comically Missing the Point of their presentation) and even push the crawling words aside as best they can.
Hey, It's That Guy!: In George and AJ, Russell is voiced by Peter Sohn, the animator on who he's based, as a result of the incomplete animatic nature of the short.
Most of the theatrical shorts with voices will have a Creator Cameo from the director or one of the animators.
The guy who does Carl's voice in George and AJ? Steve Purcell who fans of Sam & Max would know very well.