Screenwriter Richard Curtis asked for Paul McCartney's approval of the title of the film. Sir Paul gave his blessing, but also suggested they call it "Scrambled Eggs" instead. This was a lighthearted reference to the fact that before coming up with the lyrics for Yesterday, McCartney had the temporary lyrics of Scrambled Eggs as a placeholder for the song.
The Beatles had zero input creatively, outside of approving of their music being used in the film. Director Danny Boyle stated in interviews that the film was "blessed" by Paul McCartney and Ringo Starr, as well as the estates of John Lennon and George Harrison.
One early concept was that the color purple didn't exist, with a casual reference to the band Deep Purple being called "Deep Orange." The idea was abandoned because it would be too much work to make sure no extras wore purple.
Though it was not in the original script, director Danny Boyle was so taken with the discovery of a recording studio by a railway track that he had the text altered to incorporate the trains and utilize the location as Gavin's studio.