Continuity mistake: When Horatio and Delko are on the dock talking to the blond about "Diablo" on the close up shots you can see that there is a large yacht parked at the dock she is sitting on. When the camera switches to the shots from behind looking over the pool with her at the far end, the yacht is gone.
Other mistake: During the scene (towards the end of the episode) when Horatio's young wife Marisol dies, there are two worthy mentions. First is when we see Horatio walk into Marisol's room, there is a doctor present but the two do not speak. Horatio speaks to Marisol at the side of her bed and they joke about their supposed date later that night, and her speech seems fine. A few seconds later while holding her hand, we hear the "flat line" and Marisol passes away. About two seconds after we hear the flat line, the camera angle shows Marisol still turned toward Horatio, her chest still moving to breathe. A split second after that though, the camera angle now shows Marisol face up in the bed, presumably dead. Second issue and perhaps most importantly - Marisol was young, and a gunshot victim who had been in stable condition just the day before. Even if her condition had turned more critical, it seems almost impossible that as soon as she flat lined, there still would not have been immediate resuscitation attempts or calls for a resuscitation team, especially with a doctor who was already in the room.
Factual error: In the episode originally aired on 10/24/05 entitled 'Under Suspicion' Walter Dresden's DNA was positively linked to a murder in Orlando. Even if the judge dismissed the case against him in Miami, he would have been transported to Orlando to stand trial for that crime, not simply released.
Factual error: When Nikki is found dead, electrocuted in her bath by having a tanning lamp thrown into the water with her, the lamp is shown as being on, fully lit, and mysterious blue electric lights are playing about around it. However, when the CSI crew enter the room they note that the safety on the plug tripped instantly - 'just not in time'. There should have been no power to the lamp, then.
Continuity mistake: In Episode 4-12 "The Score" When Frank is standing over the body of Paul Sanders and Alex is checking him out, as he talks to Heratio he has something on his right cheek that looks like a large pimple or covered bump. In the next scene when he is interviewing Heather Larkin in the police station there is nothing on his cheek.
Revealing mistake: Season 4, episode 21: "Dead Air". At the start, when Horatio looks at the call details, it very clearly reads "no sim card inserted" at the top of the screen. Quite hard for the accidental recipient of the call to have a working phone without a sim card...
Plot hole: There is a large amount of blood found at Rachel Turner's apartment and it's determined to be Horatio's. He is subsequently arrested. Why wouldn't he be checked for a cut? To bleed that much would require a large cut and since it was only 24 hours it wouldn't have had time to heal, therefore proving that the blood although his had to be planted. That's too large an oversight by the police to just be a character mistake.
Deliberate mistake: When they are trying to find out who the blogger is, they back trace to the IP address the person is using, the IP address they find starts with 310, the highest number any octet of an IP address can be is 255.
Factual error: Delko would not be able to work on the case, since he was present at the robbery and thus an eyewitness. An eyewitness who fired his gun at that. He would have been dismissed from the case.
Plot hole: Delko pulls over Hayden early in the episode and questions him. Later on the shooter from the spa is found dead and he has glove markings on his arm. Delko tells Calleigh to compare the markings to the gloves he took off Hayden and they are a match. But Delko pulled Hayden over hours before he killed the shooter. If Delko had the glove in custody, how could Hayden have worn it during the killing?
Open Water - S4-E22
Continuity mistake: At the onset of the episode, we see the overview of the cruise ship with full sunlight, many women sunbathing on the deck, and people/staff walking around. We then hear "man overboard", and everybody on the ship's deck takes notice. Various people, including the ship's captain and the man's wife, then attempt to help the man to no avail. A few minutes later in the episode, Horatio and Delko are questioning the ship's captain about what happened and asked him about witnesses, etc. The ship's captain said "he didn't think that there weren't any witnesses around, as this happened around 6am." The ship's captain would have no reason to lie at this point, so this was totally inconsistent with the events shown just a few minutes earlier.