As a general rule I dislike literary theorizing that blathers on about constructing narratives. However, every once in a while even a deconstructionist or an academic can manage to say something that is true, useful, or interesting. Sometimes they can even manage all three at the same time.
In Antonioni’s Blow Up I think you have a case where the idea that reality is constructed can be useful in understanding the film. The photographer, Thomas, photographs Jane (Vanessa Redgrave) and her lover in a park. In the process of enlarging the photographs he sees a body in the brush. He subjects the photographs to further enlargement. Eventually he realizes that Jane and her boyfriend are looking at the corpse. Rather than ringing up the police and turning the photos over to them, he looks for the corpse again, and finds it, but because he hasn’t taken his camera with him must go, get it, and photograph the corpse. What we see in the process is that he is unable to experience reality directly. He must process it through photography, and in processing it he constructs a narrative, as he does when he hangs the enlargements so that they form a sequence showing the couple looking at the corpse. In hanging the pictures he has constructed a reality that he can understand. This reality, however, only exists as a product of the photographs, when they are stolen, he is unable to deal with the sudden lack of narrative.
The second place where reality is constructed is the mime sequence at the end. Mime is an artificial reality that demands that you, the audience, consent to the authority of the mime. Unless you buy into the mime’s world his actions, patting the invisible walls and so on, are simply foolish. Once you’ve consented to his narrative he can impose his version of reality on you. So the tennis game represents a reality to which the audience consents. They, in effect, perform a social construction of a reality in which a tennis game is taking place. They turn their heads in time with the strokes, and the imaginary flight of the ball. When it appears to go out of bounds, Thomas, by going after the ball and picking it up has consented to enter into their reality. He has, in effect, submitted himself to a socially constructed reality that is imposed on him by others.
The tennis game is not a liberation, but a submission.