Well, there's "The Mouse that Jack Built," with Jack, Mary, Rochester, Don, and Mel Blanc voicing all the characters--nice little mousie version of a fifties Jack Benny show! And as a bonus, the "commentary" sound track is actually many, many takes by a studio violinist, who just can't quite manage to make his instrument sound quite as BAD as Jack's!
But there are many other Benny moments...including "Daffy Duck and the Dinosaur," with a very Benny-esque "Casper Caveman," voiced by Jack Lescoulie ("OTHER cave men get to go in swimming. I never get to do ANYTHING."). Another is "Goofy Groceries," with "Jack Bunny" being blown up by a firecracker courtesy of a gorilla. When his face and clothes are blackened, he suddenly morphs into Rochester for the iris-out line.
There are a number of other little related moments: in "Wideo Wabbit," there's a Frank-Nelsonish floor manager on Elmer Fudd's nature show, for example. Makes me wonder if Mel's presence in the cast led the writers to think of the Benny show as source inspiration now and then!
Nice collection...and Whoopi Goldberg even makes a short appearance on each disk to explain that the ethnic humor was more acceptable "back then" than today, even though "it was wrong then, and it's wrong now."