In Fellig's apartment when he was shot, the bullet pierces the camera lens. The brand of the camera is covered. In the next shot, the brand of the camera is shown as 'Nikon'.
When Alfred Fellig is loading his film, he switches on the safe light (red/orange light). When doing photography, film must be loaded and unloaded in complete darkness. Photographic paper is safe under a red light, but film will still be ruined by it. An expert photographer would never make this mistake.
Elevators cannot crash when the cable snaps, special breaks (the great invention of Otis) are automatically activated.
Twice, Fellig took pictures in the dark without flash.
The knife pulled by the hood to stab Fellig makes the sound of a switchblade. The knife found at the crime scene, shown in close-up in the evidence bag, is a fold-out. It would not have made the sound of a switchblade, even if the hood had 'flipped' it out.