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.
Actually in this movie it doesn’t matter. Something has been hidden behind that vent which the protagonist is about to findbout in a second.We will never come back to that bathroom.
So I’ll add my list of reasons: just to visually draw attention to the vent in a neutral way. For example, to make it seem like the temperature is uncomfortably warm, or to make the audience notice something that the characters missed.
Basically vents are invisible to us cognitively speaking, so if you want people to think about them, you have to make them stand out.