Plot hole: The coroner found the ticket stub in the throat of the guy whose tongue was cut out, he died in the ER. The ER staff would have have found the ticket stub while trying to save his life. With the tongue being cut out they would have opened up his mouth to stop the bleeding.
Continuity mistake: In Episode 4-03 You Only Die Once In the beginning of the episode when Flack calls in the address of the apartment he calls in the address of 260 W 72nd Street, however, when the burglar is shown repelling down the side of the building the address on the front of the building is 535.
Plot hole: In Episode 4-4, "Times Up," it is stated that Kevin Murray will be killed at 9:45. When Mac is standing over the dead body, he looks at his watch. It is 9:45 and he says, "Right on time." Unless Mac was standing on the sidewalk when he flew out of the window, he actually would have died earlier, since it would have taken time for the police to be called and arrive on scene.
Continuity mistake: When Flack, Lindsay, and Stella go to Kim Wey Imports, it's bright daylight out. But when Flack chases Wey out of the warehouse, the sky has suddenly become pitch black. They were only inside for a few minutes, so it shouldn't have been that dark. (00:25:05 - 00:26:30)
Continuity mistake: In Episode "Happily Never After": In the opening when the CSI team is looking at the puncture wound of Fiona Chisolm, there is no blood coming from the wound. It is actually mentioned that there is no blood. Then it is determined that she was dead for about 6 hours, but now there is an L-shaped blood drip pattern to the chest wound.
Continuity mistake: Episode 19 - Personal Foul; Lindsay is going through the cheerleaders' photos to find a biometric match of the heavier woman, and she picks a head shot of a blond cheerleader. She removes it from the pile to scan it, seeing through the back, we can see what the actual picture looks like. It is a close up picture of a woman wearing big sunglasses. When the scan is complete, it is revealed as the original cheerleader photo.
Factual error: When Mac is held hostage until he can prove that the bank robber did not shoot the manager, he asks for a portable CT machine to be delivered. CT stands for computed tomography which is a machine that takes slice pictures of the body and puts them together to form a whole image. This is why a CT machine has a tube like quality to it, so it can take slice-like pictures around the body. When it arrives the machine is not a CT at all, but an ultrasound. This is made obvious when Mac uses the transducer probe (wand-like attachment) to scan the body. Anyone who has had any of these procedures done, or has seen them in TV shows, or knows how to search images on the internet can see the difference between these two very different machines.
Continuity mistake: when the bank manager's wife is being prepared for autopsy, Sid begins by taking pictures of the wife. In these shots you can see her wrists and ankles are bound with tape. First he cuts off the tape on the ankles and places it in the evidence envelope with Danny and Lindsay. Next he begins to cut the tape from the wrists. As he is doing so, the next shot cuts to a full body view of the wife in which she has the tape back on her ankles again.
Other mistake: The body in the bank has one entry wound because the gun has no kickback, but in the flashback of the manager getting shot the shooter pushes the manager back then shoots him twice, the managers body moving alone would have causes the two bullets to enter at to different points.