At the end of Who Framed Roger Rabbit?, the villain Judge Doom gets to take his own medicine: he gets doused with the toon-destroying Dip that he'd produced for use on Toontown.
The sound effect of him reacting to this is a high-pitched voice wailing over and over "Whoa-oh! I'm melting! Melting!", which is of course an iconic element of The Wizard of Oz, when the Wicked Witch gets her own comeuppance. But did Roger Rabbit use a sample of the audio from Oz? Or is it a reenactment by Christopher Lloyd, or maybe one of the voice actors on the film, like Charles Fleischer?
Further, how was it decided to incorporate this reference into the production? The character's high-pitched voice is mentioned on a few occasions, and he reverts to that voice during the climactic reveal of his disguise. Was this connection planned all along? Or did someone say later, "hey, let's do the Wicked Witch when Doom dies", and then they changed the script to incorporate the "high, squeaky voice" so that the wailing would fit in? Or the other way around: he always had the squeaky voice and then someone noticed the Witch melting similarity?