The Writers Guild of America, after sorting through the mess of writes, rewrites, and re-rewrites, decided that the screenplay is credited to Kevin Spacey and Lewis Colick who worked on it back in 1987 when Warner Bros. hired him.
During the song "Some of These Days", Kevin Spacey says "ah, do it, Sophie", as Bobby Darin did in the original recording. This is a reference to Sophie Tucker, the "Last of the Red Hot Mamas", who first recorded the song on February 24, 1911, and later re-recorded it in 1926.
When financing looked as if it might fall through just before filming was to start, Kevin Spacey persuaded Lionsgate Vice Chairman Michael Burns to get that studio on board by driving Burns around in a car and playing a medley of Bobby Darin songs. At some point Burns made an observation about Darin's singing. Then Spacey told him, "That's not Bobby Darin, that's me."