Most crime suspect interview scenes in TV cop shows would be ruled inadmissable by any court. They're often in quite a dimly lit room, with usually one cop sitting and the other pacing around, often walking behind the suspect and talking quietly in his ear. This is illegal. The room has to be well lit and ventilated and no interviewer is allowed to question from a standing position. They have to be seated and facing the suspect at all times. Of course, the dimly lit room is for dramatic purposes but I often get annoyed when I see something like this.
I'm a medical student and always shout at Holby City and Casualty when I see the staff behaving the way they do. They always have personal conversations in front of patients, like results of pregnancy tests, who fancies who, other patients etc... I'm sure the patients must all have selective deafness.
My other peeve, usually in shows like CSI, is when test results come back just at the moment that the detective walks into the lab.
Detective: Hey, you got the results of that DNA test I asked for?
Technician: Yes, it's just coming off the printer at this very moment. Lucky you walked in right at this point, isn't it?
p.s. I've just been banned from wearing my stethoscope round my neck. Let's see how long it takes for that rule to filter through to 'TV' land. You still see the white coats in some shows!!