Or maybe, because Cooper was kind of being the 'bad boy' he had a temp put on for the ballet. I'm pretty sure that Ethan Stiefel doesn't have a tattoo anyway, but I could be wrong.
I noticed this too, but Charlie also has one later, and then it disappears. I'm pretty sure that they are just temporary because a dancer (at least a ballet dancer) wouldn't dare get a tattoo where everybody could see it, since most costumes wouldn't cover it.
Hello! It was fake Ethan Stiefel(Cooper Nealson) is a principal dancer for American dance company, they are not allowed to have any visible tattoos while they are working for the company, i am most certain it was temporary to make him self look tougher. Plus at the Broadway dance studio when he was there taking the dance class with Jody it wasn't there.
Tattoos on a ballet dancer? Definitely no! Their jobs at the American Ballet Company require them to be dancers and actors, this requires stage makeup! That tattoo was part of his costume, remember he was playing the "bad boy". This is NOT a slip-up.
Okay, with the tattoo. I'm a dancer and I know many professional ballerinas and male dancers with tattoo's. During a performance you cover them with make-up. I don't think they would put a temporary on Cooper because the audience wouldn't be able to see it anyways, then again, it's just a movie, but this one I really think is a mistake!
I think we are missing the point here guys. Whether the tattoo is real or fake, the point is that it was there in one scene and disappeared in another, so whether they forgot to put on a fake, or forgot to cover up a real one, it is still a slip up.