When Jessica Rabbit sings "Why Don't You Do Right?" in Who Framed Roger Rabbit, who are the actual people who recorded the trio part (bass, drums, piano)? I've transcribed the piano fills and would love to be able to credit them to someone.
Thanks for your question. According to the film's page on IMDB, the following musicians are credited:
James Thatcher .... musician: French horn
Chuck Domanico .... musician: bass (uncredited)
Greg Fulginiti .... music engineer (uncredited)
Tom Scott .... musician: saxaphone (uncredited)
Tommy Tedesco .... musician: guitar (uncredited)
Allmusic.com credits the London Symphony Orchestra with all of the tracks in the film.
I hope this was helpful. Best of luck in your search!