Goldammer: Most of the time we were outside, and it was cold at that time of the year. And there was one scene where they are swimming in the water together. So for these days, I asked Göran to make some silicone prosthetics. They look exactly the same, but they just don’t react to water. Or when we were outside for the sex scene where they were very little dressed, and it was a very cold day, you could feel how the gelatin got just a bit tougher. And I placed hand warmers on the cheeks, and it was just enough to bring them back. We didn’t have any problems. But I mean, for them, it was a pretty tough shoot, because they had to be in very cold water, running naked through a forest, shooting outside in very little clothes.
Source: latimes.com – Los Angeles Times