Egroeg Evoli said
Isn't Tomorrow Never Knows played during the credits of one of the episodes? And doesn't somebody give somebody else Revolver?
Yes & yes. They also make a reference to A Hard Day's Night in the episode.
There is also an episode when some of the characters are tripping on LSD. On of the female characters says "I feel dead" or something close. It reminded me of She said, She said. Also in the episode Don is whistling I Want To Hold Your Hand.
Another episode Crane, attends Hare Krishna meeting and are singing ...