Character mistake: Seven minutes into the show, Sarah Sidle is about to do an internal sexual assault exam/kit on an unconscious victim in the hospital, Sarah picks up a metal speculum and says aloud to the victim (in a presumed moment of empathy), that she "never really liked this part of my yearly exam. These things are always freezing" referring to the speculum in her hands. She then brings a speculum to her mouth and begins to blow open-mouthed on it two times, forcing her hot breath on it to warm it. She then begins to insert it into the victim as the scene cuts away. This is pure stupidity, as no trained CSI would ever contaminate the tool like this. Sarah just added her own DNA to the speculum via her breath so any saliva or body fluids are now on the speculum what she is about to use on this patient, who is now also exposed to any STDs from Sarah.
Factual error: There are some majors problems with the "jumper's" crime scene. The girlfriend bashes the boyfriend on the back of his head. He bleeds out all over the balcony (she cleans up the blood with towels) but the body leaves absolutely no blood behind on the carpet (It's white\off white so blood would stain badly). She drags his body across the carpet and carpet fibers get stuck in his watchband by the adjustment knob. Dragging a body across the carpet would snag fibers on the opposite side. The CSI crew experiment and conclude the boyfriend was pushed. The blow to the head killed him instantly (coroner's report): therefore, the girlfriend would have dumped the body. Dumping a dead body over a rail would provide a different trajectory than pushing a live person and would not have matched their experiments. Finally, the boyfriend is fairly muscular and heavy. The girlfriend is petite. It would be an extremely difficult task to stand a lifeless body up at the balcony rail and flip him over. (If she could have lifted him up and over the rail, she should have been able to carry him to the balcony instead of dragging him.)
Factual error: Grissom and Catherine are looking through a microscope and discussing a microscopic specimen (heart of frozen body). In reality they would not see anything as all microscope objectives are missing on this instrument (the microscope nose-piece is totally empty.). (00:21:00)
Factual error: The show falls into the Hollywood myth on polygraphs. Jesse is given a polygraph test after pleading guilty to the 4 murders. He answers all questions, except the last one, honestly. The 4 traces on the polygraph show no real movement on these questions. On the final question, Jesse lies and all 4 traces spike. If polygraphs actually did that, they would be admissible in court. But the reality is, it is the opinion of a highly trained operator that decides if there is a lie. The average person could not look at a polygraph results and point out a lie. There is no huge, visible spike. The producers could have replaced the 4 traces with a red\green light: Green is an honest answer and red a lie.
Continuity mistake: When Holly is first in Grissom's office and says that she feels light headed, Grissom offers her a chocolate-covered grasshopper and takes one for himself. Holly asks, "Is there a grasshopper in there?" and Grissom's right hand is near his waist. When the shot changes, Grissom merely smiles and eats the grasshopper, but his hand started off much closer to his chin without there being an opportunity for him to move it.
Continuity mistake: When Sara and Warrick are interviewing Meg at the end of the episode, the scene cuts between a medium shot of the dynamic duo, a close up of Meg's face and a close up of her hands which remain clasped on the table. The first time we cut to Meg there are tears in her eyes, but her face is dry. The second time we cut to Meg, there is a drying tear track on her right cheek. The third time we cut back to her, the tear track is gone, but there is a tear halfway down her left cheek. This continues throughout the scene
Plot hole: Grissom examines the victim's body and immediately rules it a homicide because he was wearing eyeglasses. He states that suicide is a cowardly act and no coward wants to see their death and would have removed their glasses before committing suicide. What a completely unfounded, and unscientific, statement. Suicide being an act of cowardice is his opinion and not a scientific fact and they don't work off opinions: they always state how they work off the evidence.
Continuity mistake: When Catherine and Warrick are testing to find the distance the shots were fired from, when Catherine shoots at the shirt that's 2 feet away there is no gunpowder around the hole. When Warrick puts the victim's shirt next to it, for comparison, there is now an inch of gunpowder around the hole.
Revealing mistake: At the end of the episode, Grissom pins the newspaper article about the security guard's death onto the bulletin board and the camera zooms in on it. The article is three paragraphs long, however it is the same paragraph of text repeated three times. (A DVD player with a zoom feature can confirm this.) (00:44:30)
Continuity mistake: Sara takes pictures of Brenda with an UV light camera. The camera used to film the episode for broadcast is barely able to show the walls in the background as tiled. When the UV pictures of Brenda are used in the interrogation, the photos show Brenda's back up against the tile wall.
Plot hole: A head without a body is found early in the show. Then, a body that has been decapitated, skinned, and severed of hands and feet is found. The CSI team assume the two are related until the coroner states that the body isn't even human. He also mentions that he has no idea what kind of animal it is and they'll need to consult an anthropologist. Everyone is shocked to learn the body is that of a gorilla. The body is humanoid (2 arms, 2 legs). It is larger than human size. The only thing it can possibly be is a gorilla. It must be a primate for having a humanoid shape and must be a gorilla because that is the only primate larger than man. There was no need to bring in an anthropologist (which should have been a zoologist if they truly had NO idea what kind of animal it was). It should have been painfully obvious to the CSI team, who are experts in all fields, that the body was a gorilla.