When Eric walks into his hotel room, he tells one of the guys that he is going to go do laps. He leaves in his suit. Later Gracie talks to him while he is in the pool, and he has on his swimsuit and goggles--did he have those on underneath his suit?? I don't think so!!!
I don't think that he was sleeping in that room. There were so many guys there that it was impossible for them to all stay in the one room. It seemed to me that the room was a headquarters of some kind. He probably went back to the room where he was sleeping and had his clothes to change.