From Andrew Davies:
I think the first shot of Christopher Nolan's "Memento" could be best described as the film in miniature because of how the subject of the shot establishes several important elements of the film. The credits begin on a dark screen. The title "MEMENTO" is still there as the shot fades in, placing the title over the image of a hand holding a photograph. Placing the title over the image of the photograph links the word and the image, telling the audience this photograph is a memento of...something.
The photograph, which is that of a man dead on the floor, his blood on the wall and floor, establishes several important things about the film. The photograph first establishes the narrative structure of the film because as it is shaken, the picture fades instead of develops. This represents how the film begins at the end of the story and progresses, so to speak, to the beginning. The fading of the photograph also establishes the mental state of its main character, the man holding the photograph, Leonard Shelby (Guy Pearce). Like the photograph, Leonard's memory fades. He has short term memory loss, caused by an intruder who raped and murdered his wife in a home break in. His mission through the film is to find "John G," the name he gives to the intruder. The photograph, in of itself, establishes one of the ways in which Leonard tries to keep track of people and places he will forget is to take photographs of them, writing captions underneath the picture.
Finally, the photograph sets up the first mystery of the film, which is who the dead man in the photograph is and who killed him. Even when we learn who the dead man is, Teddy (Joe Pantoliano), and that Leonard has killed him, we will spend the entire movie trying to figure out whom these two men really are and their relationship to each other. Teddy taunts Leonard by telling him that "you don't know who you are." Memento makes us reflect on the fragility of our own sense of identity and how like Leonard, we alter and distort our memories in order to justify our actions and to create meaning in our lives, regardless of who gets hurt. The fading of the photograph ultimately represents how Teddy will vanish from Leonard's memory as he possibly hunts another "John G" or maybe gives up his hunt entirely.
JE: This shot is so simple (it's also the background for the opening credits) and, as you say, it works in so many ways. To start with, it's a striking piece of graphic design, and a widescreen composition that's both bold and subtle. Of course, your eye immediately goes to the red (blood) in the photograph, but you also notice right away that there's a hand holding it. Which means someone is looking at it... from roughly the same position that we are. And then there's that little bit of indecipherable writing on the hand. What is going on in this picture? We're left to wonder throughout the duration of the shot, and the more we learn, the more the mystery deepens.
The first time the hand shakes the Polaroid picture, we might feel a little confused: Did that photo just fade a little? After the second shake, we realize that the exposed film is "undeveloping" -- that we're seeing time run backwards. What's particularly great about this is that no explanation is offered. (One of the major criticisms of Nolan screenplays is that they over-explain everything in dialog or narration rather than presenting things in such a way that gives the audience the satisfaction of piecing things together for themselves.) Of course, this becomes explicit when we see the picture go back into the camera and the bullet shell go back into the gun.
Unfortunately, the explanations of Leonard's "condition" or "handicap" are forthcoming all too soon. Nolan has never quite learned to trust his audience without lecturing (or hasn't developed the skill of communicating information and ideas indirectly), but at least we get the pleasure of not understanding for a little while, and the pieces don't all quite fall together until the end. I think that's why "Memento" remains my favorite Nolan puzzle-picture.