Awesome Music: Neil Innes' songs imitated the Beatles songs so well that they wound up on Beatles bootleg albums, and one fan actually accused him of stealing "Cheese And Onions" from an unreleased Beatles tape. He was taken to court for the songs, and had to testify that he hadn't listened to the original songs while making the soundtrack, just wrote from memory. There's no way to deny that's stunning.
Hilarious in Hindsight: When John Lennon watched the movie, he told them that the songs they did ("Get Up and Go" in particular) were too close to the real thing and that Paul might sue them. That actually happened.