Factual error: Near the end of the movie, a DJ announces over the air that the crash had occurred that killed Buddy Holly, J.P. Richardson (commonly known as "The Big Bopper"), and Ritchie Valens. The DJ then plays the Santo & Johnny tune "Sleep Walk" as a tribute to the lost musicians. The crash occurred on Feb 3, 1959 (and one would assume the radio news announcement was within 24 hours of the crash). The song "Sleep Walk" was not released until July 1959.
Factual error: Buddy Holly is seen singing 'Cryin', Waitin' Hoping' at the Winter Dance Party. He hadn't actually finished composing this song, never mind recording it as a finished piece of work when he went on his final tour. This song comes from his final recordings 'The Apartment Sessions' which he recorded in New York and was finally released after his death, complete with added backing music and vocals.
Factual error: The film depicts the coin toss between Valens and one of Holly's band members, Tommy Allsup, as having taken place at the airport shortly before takeoff, with Holly having tossed the coin. In real life, the coin toss took place at the Surf Ballroom when Tommy Allsup, after being asked numerous times by Valens to "let me fly", finally pulled a fifty cent coin out of his pocket and said "Call it." Valens called heads and won.