Not everybody in the family is thrilled with the film, however. J.C. Unitas, Johnny's grandson and a 24-year-old former Villanova quarterback, wrote on Facebook that Flacco is an "embarrassing choice" to portray the former Baltimore Colts great.
"My grandfather and his legacy deserves only the best, and this is not it," J.C. said. "Has Baltimore forgotten that Trent Dilfer also won a Super Bowl while playing for Baltimore?"
The film, based on a book written by Tom Callahan, is being produced by Joe, Johnny's son from his second marriage. Expected to hit theaters in 2014, the film has touched off a family feud between Joe and half-brother John Jr., Johnny's eldest son from his first marriage.
"It is awful. The guy's a turd," John Jr. told USA TODAY Sports on Sunday. "He never talked to me. He never talked to any of the first five children. He's a guy that's just making money off of my father."
This won't be the last we hear from John Jr. about the film. He's considering legal recourse if Joe turns a profit.
"They're trying to do anything on the coattails of my father's name," John Jr. said. "It's like prostituting yourself. My father would have nothing to do with it. It makes me angry, but there's nothing I can do about it until they slip up."
Follow Chris Wesseling on Twitter @ChrisWesseling.