Nate came out of the bathroom, how could he not know?
After Sonny left, Nate came out of the bathroom and asked where the baby was and Vanessa replied he was in the tub, so how could Nate not know?
shareIt's been awhile since you posted this question. The impression I got from that scene is that Nate rushed into the bathroom to hide when Sonny came home to look for his keys. He probably didn't look around the bathroom because he was listening to Sonny and Vanessa's conversation. He was so worried about being caught that he didn't have time/interest in snooping through the bathroom. Also, although the bathroom was never shown, it could be that Vanessa pulled the shower curtain closed.
I always wondered about that whole setup simply because six month olds are usually not mobile yet so the baby either had to be within reach of the faucet handle or somehow bumped it. I don't know if a six month old could do that. It seems like the baby was just the prop to move the story along regarding Vanessa's fidelity. An older infant would be more interactive but a six month old really isn't old enough to be mobile yet.
Get busy living, or get busy dying. Andy (The Shawshank Redemption)