This is because you can see the white curtain, no cover on the window and the lighting is different to the rest of the shots filmed in this area. This is because orginally, at the start of our first filming day, two covers were used on the window. However, when we attempted the shots where the cover was pulled from the window, the second cover posed a problem and stopped the window being uncovered properly. We then removed the second cover, and had just the one. Unfortunately, while all the other footage was re-shot without the second cover, this part was forgotten. Due to this, at the start of our second day of filming we attempted to film this shot again, and got the above.
After looking through footage to see if there was a better shot we could use instead, I found some of the footage with the two covers that I was not intending to use, which featured this shot with the covers, and the same lighting as the rest.
Its not very obvious here, but the second cover can be seen. However, I felt it would be better to use this shot rather than the out of place looking other shot. So, I cropped the shot so that the cover was no longer visible.