When Klaus Voormann introduces himself to the Beatles, he mentions that he's an artist and lays a stack of album covers on the bar. Voorman would later go on to create the covers for The Beatles albums "Revolver" and "The Beatles Anthology" (One large painting cut into thirds for the three volumes).
The soundtrack does not feature any Lennon-McCartney compositions, presumably for budgetary reasons. However, the film does include many songs covered by the Beatles as part of their well-known Hamburg/Cavern Club repertoire. Among these are "Twist and Shout" (later to appear on their debut album "Please Please Me") and "Long Tall Sally" (later released on an EP of the same name).
1990s punk-rock musicians and techniques were used to create the film's soundtrack, instead of the precise styles of the period, to better convey the way the music felt to the early Beatles audiences; "it was the punk of its day".
Stephen Dorff was the only actor of the group who could actually play his instrument (he's a professional musician in real life). Ironically, his character, Stuart Sutcliffe, could not play his instrument, which is one of the chief reasons the real Paul McCartney later cited as to why he wanted Stuart out of the band.