Continuity mistake: As Mike scrolls through the microfilm, we see his view as the pages scroll from right to left. The shot then reverses to show his face through the scrolling film, but while the film is now properly reversed, it's still moving right to left in our view. But this reversed angle should show it moving left to right.
Question: What is the significance of the crazed woman (wielding a hammer, wearing a jacket, frizzled hair) that appears several times throughout the movie? What does she represent? She appears during the scene where Mike Enslin notices his doppelganger in the window across the street from him, once in a quick shot with her holding up her hammer, and she shows up for the last time as a character in the painting of a ship lost at sea as the room falls apart.