Go to the part where Bosley is in the castle thing and he is trying to escape. (The part where he ties the sheet to the window bars) Look at the window in the next few scenes, it's dark then bright and dark and bright again. And the when you see "Thin Creepy Guy" it's dark again.
If you have the DVD version, listen to the Commentary Track. You hear McG (the director) say that the scene was actually night time when they filmed it, then edited it to day time later on, using CG. They must have forgotten to edit through the window! Good job!