Stephen Meyers (Ryan Gosling) says about a slur on his opponent, "I don't care if it's true. I just want to hear him denying it." This is a reference to a statement attributed to Lyndon B. Johnson, who allegedly referred to an opponent as having carnal knowledge of farm animals. When an aide said he couldn't say that because it wasn't true, Johnson replied, "I know but I just want to hear him deny it."
The Ides of March is March 15, notable as the day on which Julius Caesar was assassinated. In Shakespeare's "Julius Caesar," before being stabbed to death, Caesar is told by a Soothsayer: "Beware the ides of March."
Leonardo DiCaprio dropped out of the role of Stephen Meyers, but he stayed on as executive producer through his company Appian Way. Chris Pine was then considered before Ryan Gosling was cast.
As stated in the DVD audio commentary, the bar Head First, where Stephen meets Tom Duffy, is located directly across the street from the Cincinnati Reds baseball stadium. It's named for Pete Rose, who would often slide head first into bases. Paul Giamatti, who plays Tom Duffy, is the son of the late Bart Giamatti, who as the Commissioner of Baseball imposed the lifetime ban on Pete Rose.