Product Placement in Plan 9

[Flick James]

I was recently watching Plan 9 From Outer Space, and I noticed a scene where some characters were sitting around and drinking bottles of Coca-Cola. It was quite clear and you could see the logos. Now, I'm pretty sure there was not product placement arrangement with Coca-Cola, so I wonder if this ever became a trademark issue. Does anyone know the answer to that?

[Skull]

Something is telling me if there was a product placement in Plan 9 it was by Pepsi; they were hoping Plan 9 would move people away from Coca-Cola...