Ringo Starr said he did not remember the genesis of the 30-second piece of music featured in The Beatles' first movie, A Hard Day's Night, in the scene where they are on a train. What has become known as "Train Music" is believed to be an unreleased Beatles recording.
The answer may lie in the 2008 book Way Beyond Compare (The Beatles' Recorded Legacy Volume 1), in which author John Winn writes, "Film producer Walter Shenson eventually verified the music was actually performed by The Beatles, presumably during the sessions for the soundtrack the week prior to the start of the filming (February 25th to March 1st, 1964). It's an entirely instrumental fragment, performed in E major with John [Lennon] playing a Chuck Berry-like boogie pattern and George [Harrison] wailing away on lead guitar."
In celebration of its 50th anniversary, A Hard Day's Night has been restored and remastered, and released on DVD. It's also being screened in theaters around the country.