On September 1967, The Beatles returned to EMI Studio 2 in order to complete the instrumental "Flying" (originally entitled "Aerial Tour Instrumental"). In order to do this, the first order of business was to overdub Ringo shaking percussion while George Harrison added guitar licks.
To end the song, the original "dixieland" ending was discarded in favour of having mellotron tape loops playing at the end. This plan was probably devised by John and Ringo as both were experimenting with the keyboard instrument around this time.
There are five passages to the tape loops: the first passage appears on the commercial version and is faded out slowly. The original first passage lasts about a minute and a half, next is a passage lasting two and a half minutes and the third lasting only about forty second. The fourth passage can be heard for a about forty-five seconds and the last passage is played at almost two and a half minutes.
This can be very tedious listening - the first passage is played backwards and the other forwards, they are the sounds of flutes and they waver as the are played.
If you are looking for the full passages, you can hear it on bootlegs such as the CD "The Ultimate Collection, Volume One: Miscellanesou Tracks" and various "Magical Mystery Tour" outtake bootlegs.