 When the producers approached The Beatles (qv) about this film,  the group, which hated the TV cartoon show of them, agreed to it  only as an easy way of completing their movie contract. As such,  they contributed only a few old songs and four quickly produced  numbers: "Only a Northern Song", "Hey Bulldog", "All Together Now"  and "Its All Too Much". However, when they saw the finished film,  they were so impressed by it that they decided to appear in a short  live action epilogue to the film.