Flag Day “is suffused with what you might call the Penn Darkness Factor. It tells the story of the richly troubled, twisted, and touching relationship between a father, John Vogel, played by Sean Penn as one of the most scurrilous dads in the history of movies, and his daughter, Jennifer, played by Penn’s own daughter, Dylan Penn, who gives a fantastic performance. Yet this scoundrel father, who she has systematically learned not to trust, is the only father she has.
“That’s the story Flag Day tells, and it’s the reason the movie hits such a universal nerve. The wrenching pain of it is that he’s a counterfeit father who’s also the real deal.” — from Owen Gleiberman’s 7.10.21 Variety review.