Jack O'Connell is flashing his cock in that movie. It's brief but we can see his uncut dick. Jack O'Connell is somewhat erect, reasonably thick but not that long.

40 minutes in the movie, Romain Duris is crossed dressing. Overall we see him shirtless in many scenes of the movie. There is only one scene with full frontal and rear nudity. 74 minutes in the movie, Romain Duris is naked, chasing his girlfriend. We see his butt and also his long cut penis flopping around as he runs.