In an older thread, Gergely Hubai (The Cat) mentioned this:
"And there's a very good reason for you not hearing a single note of this. Don't expect this anytime soon."
"I gave you more information than anyone before. I told you the score actually exists, the music survives and it's not being released for a reason. I can't imagine how the nitty-gritty legal stuff would be of any interest. Needless to say, if the matter is resolved, I'll be happy that you get the chance to hear the music.
Bernstein's "Rat Race" music moved a bit more along the "Airplane!" aesthetitcs without that score's historic importance or genuine wit. But I'm sure that if it may get released one day, it will find its fans."
This is one of the following rejected scores by Bernstein that still have not been officially released:
"Casey's Shadow" "A Night In the Life of Jimmy Reardon" "Trust Me" "Murder In Mississippi" "Innocent Blood" "A River Runs Through It" "I Love Trouble"
I was told that he had another score rejected later around the end of his career that wasn't fully recorded, but all the late rejections were fully recorded, so that leaves one mystery titles. Off the top of my head, there's one possible film that fits: "Casino" (which ended up with no original score).