Filming: Yellow Submarine cameo
Paul and Ringo still looked similar to their animated counterparts, but George and John had shaved off their moustaches and John had grown his famous lamb chop sideburns.
The Beatles were contractually obligated to appear in the film, so they needed to get this scene out of the way before setting off for India. But as it was an animated film and the Beatles had such a small role, United Artists didn't consider it sufficient enough to fulfil their contract. It wasn't until the Let It Be documentary that the studio got their third film from the band.
The shot was originally going to have a big-budget psychedelic background and effects made in post-production, but due to time constraints a simple black background was used. The scene appears towards the end of the film, as the band introduces All Together Now.