Have you tried taking the photo out of the frame and looking at the back of the actual photo? You might see something (like a studio name, a signature etc.) There might be some other tell-tale signs of age that reveal themselves when you remove it. The mat or photo may show some signs of long-term exposure to light.
The wet sand under the girls feet makes me think this isn't a posed modern studio nostalgia print. It looks like it goes back all the way to the guys standing behind them, that they are not a studio background. The hair styles are throwing me too... but I'm not ready to write this one off just yet. 
Thing is, how is the boots they wear so clean? I am not going to swear this is studio made, but it does give that presence that it is, what is that girl on the right standing on?
it still throws me off due to the trophy being held to, but their is definately something not right about the girl on the right who holding the trophy to, thats what kind of has me thrown off.
But I am not sure on where the studio background is if their is one, but it does look like the far background looks like a background from a studio, it just doesnt have that focus and its as if the flash from the camera blurred it out.
