What kills me is when they go in after bad guys or looking for evidence with little, two cell flashlights instead of the big, lightweight, rechargeable 10-20 million candlepower hand-held spotlights.
As well, luminol, the stuff they spray to find bloodstains, is insanely toxic....in real life, the investigators leave, and guys in enviro-suits and self contained breathers come in and spray the luminol, and after 30 minutes, once it has dried, the investigators are allowed back in.
More, real CSIs wear cleansuits, hair-covers, booties, and gloves at scenes, but I guess that the cast of CSI just do not look glamorous enough that way.
Also, CSIs do not carry guns, interview suspects, or even run lab tests...and in both the US and Canada, CSIs are police....ex regular cops that specialise...not civilians/academics that become CSIs.
I like CSI, but it is really, really innacurate.