"The CSI Effect": The investigation team routinely photograph the crime scene before allowing evidence to be touched or moved. Many times, however, a piece of evidence is picked up and handled before being photographed.
In the episodes where the blood is spattered or in a large pool, the pattern of the blood varies from scene to scene. For example: A man is killed and the blood is sprayed across a desk. The pattern in scene 1 (finding the body) will be different than in scene 2 (going back to the crime scene for further evidence).
In many episodes, a suspect is found because a gun was registered to them or someone is threatened with the charge of "possession of an unregistered firearm", or some other reference is made to a firearms registration database. The state of Florida has fairly relaxed gun control laws, and there is no gun registration system anywhere in the state.
"The CSI Effect": In many occasions, when arresting a suspect, Horatio's team is able to exact a confession but never the Miranda's right are read to the suspect, which can and will be used to render the confession unusable in a court of law.
CSIs are not detectives as this is exceedingly rare in real life, as they are actually classed as civilian employees. It is considered an inappropriate and improbable practice to allow CSI personnel to be involved in detective work as it would compromise the impartiality of scientific evidence and would be impracticably time-consuming.
"The CSI Effect": While often the science and technology portrayed in the series (as well as the other CSI series) is accurate or mirrors sound scientific principle, there have been times when methods have led to results simply not possible in the real world.
"The CSI Effect": Numerous times, autopsies are conducted by people who were wearing the same clothes they wore in the field. Not only does this promote cross-contamination, but it is also highly unsanitary as well as an OSHA violation. Also, numerous times when Alexx is performing the autopsy, she has a mask tied around her neck but is not actually wearing it. This mask would always be worn during autopsy to protect the person performing it from breathing in airborne pathogens the body may put into the air. Her hair is also not tied up or covered, which could also cause cross contamination.
In the Czech dubbing of the series, the female character Maxine Valera is often referred to as a man, "Valera" being "his" first name. This is caused by the lack of knowledge of the translators in terms of first name/last name usage in the United States. In Czech, a name sounding similar to "Valera" would be men's name.
On numerous occasions, suspects are given a "perp walk" from the front door of the police building to a waiting squad car or jail bus. While this provides for good drama (reporters, angry relatives of dead victims, etc.), such prisoner transfers are supposed to take place away from public view, to avoid the public spectacle portrayed in the show.
"The CSI Effect": In many episodes the CSI team are shown taking photos from crime scenes, then enlarging and enhancing them to get clues that let them solve that weeks crime. But in many instances, the original photo is blurry and out of focus and no matter how much you enlarge and enhance it you would not get the clear image of the clue that they always get on the CSI series.