Josh Brolin prepared for his role as George W. Bush by telephoning hotels and talking to the people simply to hear the accent. He also watched videos of Bush to try and get the style of his walk right.
Christian Bale was initially cast as George W. Bush, and even underwent weeks of prosthetics tests before filming began. However, he withdrew from the production at the last minute, prompting Oliver Stone to immediately look for a replacement. Josh Brolin was subsequently given the role following his notable performances in No Country for Old Men (2007) and American Gangster (2007).
When reciting the names of the fraternity brothers during his hazing, The second and third surnames of people he names are "Hill" and "Hotchkiss." Both Oliver Stone and James Cromwell attended the Hill School, whose principal rival was Hotchkiss School.
When W. enters the Oval Office at the end, there's a portrait of John Quincy Adams hanging above his head. Adams is the only other son of a former President to be elected President.