Why is it in Hollywood movies every time there is a vent or AC unit someone has fixed little ribbons on it? Is that a thing americans do? Why? The vent in this movie is close to the floor in the toilets of a train. This implies someone got on all fours ON THE FLOOR OF A TRAIN’S BATHROOM to stick those ribbons there for a reason i can’t even begin to comprehend.
It’s to show the viewer when the vent is on or off. Typically only when the fact of it being on or off is important.
It is strictly irrelevant to this scene, for example.