Didier Ghez has showcased a miracle of sorts on his always informative and wonderful Disney History blog. The Disney-produced animated sequence from the 1934 20th Century Fox film Servants' Entrance has long been beyond reach, but Didier has secured a copy and generously made it available via YouTube and his site.
The animation features kitchen utensils, led by a Humpty Dumpty-style egg character in a musical vignette that quite deftly for its time mixed live action and animation. As to the context of Disney producing material for other studios, author Michael Barrier noted in his book Hollywood Cartoons:
"In the early thirties, Disney ventured briefly into making animated inserts for two live-action features, Servants' Entrance and Hollywood Party, both released in 1934. He evidently saw such work as a way to ease into the making of his own features, but the inserts turned out to be more a source of irritation than of profit of any kind. Such sponsored films were inherently problematic, in Disney's scheme of things, because they were not under his control in the way that his shorts and features were. Once the feature inserts were behind him, Disney shunned most sponsored films."
I profiled Disney's contribution to the movie Hollywood Party in a post here at 2719 in November of 2006. The Disney Studio also reportedly contributed animation to the 1933 film My Lips Betray. That footage has yet to surface; according the IMDB an incomplete print of the film survives in the UCLA Film and Television Archives.