Charlie relieves himself next to a dumpster in a parking lot, but as he walks away there is no evidence of this.
The visible part of Jack's neck tattoo changes from a roundish, spider web-looking design, to what appears to the the tips of a flying creature's wings.
At the movie's beginning, Jack is standing nude facing the ocean. A moment later, after entering the water, bathing trunks can be seen below the water line.
You can see Charlie's reflection in glass while he sits next to Diana on the bench, as if the shot has been taken through a neutral density filter in order to use a large aperture.