Not the barbershop quartet.
Walt Disney's last personally-supervised animated feature was released on this date in 1967, ten months after Disney's death from lung cancer in the hospital across the street from his studio. ...
Vance Gerry, one of the story artists on JB, told me more than once that Walt brushed off artists' complaints that the story didn't hold together. Vance related that Walt said not to worry, the episodic plot wasn't going to be a problem.
He turned out to be right.
On the other hand, as President Emeritus Tom Sito points out:
At the end sequence, Mowgli meets four vultures who talk like the Beatles but sing barbershop quartet.
That’s because the characters were supposed to sing a Beatles parody song, but Walt felt the group would soon be forgotten. He didn't want to date the film. ...
Only proving that even movie geniuses are occasionally wrong.