When the manager Bill fired Sy he should have had Sy turn in his uniform, employee identification and store keys, therefore Sy would not have been able to steal the knife. However, just as Sy made copies of photos for himself, he easily could have made illicit copies of his store keys.
When Sy runs into Will Yorkin in Save-Mart, Will asks if a certain cable will work with his Mac. The second associate tells him no, that this is just PC. However, the cable he had picked up was a USB 2.0 cable which works with both PC and Mac.
Sy and the AGFA engineer discuss a ".3 blue shift", but Sy later tells his manager that the shift is towards cyan. (Although in layman's terms "cyan" is light-blue, blue is technically an equal mixture of cyan and magenta. A photo technician would not use the terms interchangeably).
When Sy is taking pictures of Bill Owens' (the Savmart Manager) daughter, the camera can be seen auto focusing. When he gets the pictures developed, the shots are obviously zoomed in. The camera did not zoom while he was taking pictures though.
When Nina first gives Sy rolls film to develop it is consumer grade Fujifilm Color 400 as it goes into the machine. On the internal rollers and after he develops it, the film changes to Kodak Portra (400VC)
When Mrs. Yorkin drops off film, she leaves three rolls of Fuji Superia film, distinguished by its green and blue canisters. When Sy goes to inspect the film, he holds it up to the light and the edgeprint of the film is visible. The edgeprint reads "Portra 160 NC", which is a Kodak professional film.
Near the start of the film when Nina and Jake are driving to the mall, Jake points to an open parking space to his right. Nina starts to turn the steering wheel to the right but the next shot shows the car turning left into the space.
When Sy pulls over behind Nina's SUV his turn signal is on from the outside of the car but the arrow is not flashing on the dashboard instrument cluster. Also, the speed of the clicking of the turn signal inside the car is much faster than the blinking is on the outside.
When Sy is taking his last walk through SaveMart, he speaks with Yoshi then is shown walking down an asile (2a and 2b). The boxes in the walking shot are different than what is behind Sy when he is saying good-bye to Yoshi. Note boxes sitting on their face or back in one of the sections. They are there when he is speaking with Yoshi, but not in the Steadicam, walking shot.
When Sy gets out of his car and starts to snapshot his chief's daughter, he is holding a photo camera with "Minolta aspherical lens" printed around the lens. Next second there is only "Aspherical lens" around.
When Sy is sitting in Mr. Owen's office, the position of his hands instantaneously change between camera angles. At first his right hand is rested on his left forearm, then instantly switches to his fingers being interlaced, then back to the previous position.
Red light is added by the filmmakers to show the film moving through the developing machine. Color film is sensitive to all light, therefore all of that film would be fogged. Red light is only used for black and white paper print developing.
When the detectives go to Sy's apartment looking for Sy, they allow the landlord to come into the apartment with them. Detectives would not allow this, for they don't yet know what danger they might be walking into.
Sy's mugshot photos are taken with a digital camera and processed on a computer. Law enforcement agencies never have, and probably never will, develop crime photos digitally. Law enforcement agencies and archives use film over digital because it doesn't degrade as rapidly as digital media, it is much more difficult to edit/manipulate and it comes out much clearer than a digital image ever has.
When Seymour is following Nina's SUV in his Toyota Echo, the "door ajar" light is on, which probably indicates that the car is on a trailer with one or more of its doors open or even removed (although it *is* possible that he really was driving with one of the doors improperly shut - it's not unheard of, after all).
When Sy is looking through the photos at the yard sale, a different person's hand is used in one of the close-ups; it's obviously a different thumb than in the previous and following shots. This happens again later in close-ups of Sy's hands as well.
On the Monday when Sy introduces his regular customers, when we first meet Mr. Siskind, the same two customers appear to walk the same path over again between the shots of him and Sy. Next when we meet Mrs. Van Unworth, the same thing happens: We see two customers who walk a specific path once, and then over again between shots implying they are walking along pre-marked paths.
The goof items below may give away important plot points.
Even though Detective Van Der Zee is desperately trying to reach Will Yorkin's room in the hotel and no one answers, he doesn't send anyone up from the hotel. An experienced Detective certainly would have done this, especially since he didn't know there was no real danger at the moment.
As Van Der Zee begins the questioning, he places on the table the manila envelope containing Sy's photographs, and a brown folder face down on top of the envelope. When we return to the interrogation near the end of the film, the folder is momentarily face up with the envelope on top, but in the next shot, the folder once again is face down, obscuring the envelope.