She noticed that the door to her children's bedroom was completely open, the window was also open, the shutters raised and the curtains open, while she was certain of having closed them all as she always did.
First statement to the PJ (4th of May)
On our arrival we had lowered the blind-style shutters on the outside of the windows, which were controlled from the inside, and closed the curtains. We left them that way all week. This early in the season, the nights were not that warm, there was no need to open a window
in "Madeleine"
When I realized Madeleine wasn’t actually there, I went through to our bedroom to see if she’d got into our bed. That would explain the open door. On the discovery of another empty bed, the first wave of panic hit me. As I ran back into the children’s room the closed curtains flew up in a gust of wind. My heart lurched as I saw now that, behind them, the window was wide open and the shutters on the outside raised all the way up.
in "Madeleine"
(In the documentary it is when the curtains whoosh that she sees Madeleine isn't in her bed.)
Thanks to Icabodcrane who pinpointed our attention on this change and the motive for it.