Note: I don't watch it religiously or even regularly, just when it takes my fancy and nothing else is on. Not a problem because the episodes are usually standalone cases.
Now, one of the main things they say about CSI is that it's allegedly very realistic in portraying the forensics and scientific sides of the investigations. I'm not an expert in genetics, biology and other sciences so I'm concentrating on something that really irritated me today.
In today's Las Vegas episode on 5, one of CSI types (Sara?) used what was clearly a digital SLR as if it was a compact with a display viewfinder, i.e. she was holding the camera away from her face and was looking at the display. SLRs don't work like that (when you're not taking a picture, the mirror's down so the image is reflected from the lens to the optical viewfinder, when you release the shutter, the mirror flips and reflects the image onto the film/sensor), you don't have a "live picture" on the display! On top of that, the sound you heard was that of a film SLR with motor (i.e. the mirror action with the short film transport sound after).
If they can't get a simple mechanical detail like that right, I have not a lot of confidence in their "science", either.
Then there's the fantasy computers but that's US TV heritage, I'm used to that. My old X-Files spoof RPG even had the "Tapping Keys Randomly" ability instead of Computers. ;oÞ