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.
When Brahms breaks into the crawlspace with the harpoon, he is missing his mask as he steps inside. But the mask is present during the chase scenes immediately following.
The telephone in the house makes the USA dead tone (blips) rather than the UK dead tone (a continuous tone).
It's clear from the vegetation and the terrain that the film , while set in England, wasn't shot there.
The number plate of the taxi in the opening scene does not match the British style of number plates. British plates are in the style of AB11 CDE or A123 BCE.
The house in the movie is not typical of those seen in the United Kingdom, more in line with those in America.