After Greta's first nightmare,she woke up and went to Brahms room where it was sitting in the chair with water in it's face looking like a tear, in this part she had a white shirt. She grabs it and puts it on bed and the next shoot she was looking to the attic in the room but with a blue shirt.
The goof item below may give away important plot points.
As Greta, Malcom, and Brahms run through the passages behind the walls, the walls have gaps between the slats that allow Brahms to spy into the rooms. Yet none of the interior walls are shown to be run down like this; all are painted or papered.