Factual error: In a number of episodes people are shown eating and drinking in the laboratories. For instance, in "Miss Willows' Regrets" Nick and Greg are seen eating fried chicken in the lab, and in "Overload" Sara eats a sandwich while watching Grissom experiment with her deli pickle. There are other examples. No reputable laboratory (which this is supposed to be) would allow its staff to eat or drink while in the lab. It is basic scientific protocol to prevent contamination of samples or the person picking up toxins on their food.
Deliberate mistake: Every time the investigators deal with IP-addresses, the addresses on display are impossible. Each of the four parts of an IP-address has to be between 0 and 255. As they do have to use IP-addresses some time, they could use addresses starting with 10. Those would be real addresses although not used as an official IP-address. This isn't the same as phone numbers using 555 - any IP address over 255 just wouldn't work. It would be like mentioning a phone number which uses the symbol for pi.
Plot hole: Lizzie had the car towed to icebox canyon. When you see her watching the car being lowered onto Sara, there is no tow truck there, there is no sound of any machinery lowering the car, and when the shot pans back there is nothing there that would have helped her move the car. She is not strong enough to hold up a car, put an unconscious person under it while holding it up, and then lower it without some kind of winch.
Factual error: The CSI doesn't prioritize cases by importance, and have samples from big cases go first like they do on the show. They don't have the lab in house like on the show. It's too expensive. They have to send samples from even the most important cases, to labs where it takes weeks to months to test DNA to keep down costs. They also have to do this to make sure DNA testing is done correctly. DNA has to be tested multiple times because mistakes can be made.