There is only one scene in the movie where Rupert Evans is fully naked on the bed and we can see his penis as he is making love to a woman.
As he is lying on a bed, for a few frames we can see Rupert Evans big uncut dick.

In this series, Justin Kirk shows us in large cut penis as he is having a medical exam. We see his dick sideways as he is lying down the exam table. We can however see his circumcised penis very clearly. In a different episode, Patrick Wilson get naked on the beach. Although the scene is filmed from behind, we see Patrick Wilson's large penis and balls in between his legs. He is also circumcised.

65 minutes in the movie, Damien Chapelle is naked in bed. But we only see him partially. We see his pubes.

66 minutes in the movie, Damien Chapelle is standing naked. The room is rather dark but brighter at moment and we can see his uncut dick.

We get to see this group of young guys at the swimming pool. A lot of nudity in the showers but none that we can really distinguish, except for Toby Hemingway. We can see his butt as he walks down the locker room. It's interesting to see that Chace Crawford is also in the movie, but no nudity from him below the waist. Just a great hairless body and an angel's face.

Alfie Allen is naked 16 minutes in episode 5 of season 1.
He proudly shows us his massive uncut dock. As his fellow actress says, he is a "serious boy with a serious cock".

Later in the episode, we get a partial butt shot of Gethin Anthony, after he gets a complete shave from his boyfriend Finn Jones.

8 minutes in episode 4 of season 1, Alexandros Malaos walks into a room wearing only a t-shirt. We first see his uncut dick.
Then he gets into a fight with Chris Zylka, and we see more of Alexandros Malaos's penis and butt.

5 minutes in the movie, we see Franco Merli naked.
17 minutes in the movie, an uncredited black man is also naked. He is hung like a donkey. We can see his erect dick from behind in between his legs.
He is cut.
60 minutes in the movie, we see Ninetto Davoli's butt, and then his uncut dick.
Again we see both his butt and cock 63 minutes in the movie.

7 minutes in the the pilot episode, Jamie Campbell Bower is naked but we don't see much.
20 minutes in the episode, James Purefoy is naked making love to a woman. When he flips over her, we clearly see his butt.
44 minutes in the movie, Jamie Campbell Bower is dreaming. In his dreams he is naked. We see his nice butt as he is making love to a girl.