According to The Beatles, they were experimenting with marijuana at the time this movie was filmed. That explains why they flub a lot of their lines or their lines don't make much sense.
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Algernon: Sort of a long counterfoil!
The Semaphore Flags held by The Beatles on the poster (and album cover) don't spell HELP, but NUJV. This was done deliberately because the photographer of the cover, Robert Freeman, thought that it doesn't look good, therefore the flag postures were improvised, therefore it's not an actual error.
During the closing credits, you can see Paul McCartney take a bong hit, then proceed to blow smoke into the camera.
When released on video for the first time in 1989, the film remained in mono but the songs were remixed into stereo, dubbed over with the recordings from the stereo album.
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