Peeve 1: Guessing a password.
GAH! This one bugs the crap out of me! Especially when the password guessed is something simple. Simple as in a single word with no special capitalization, numerals, or other special characters. I have to have at least three different types of characters in my password and it's changed every 90 days. If my new password is too similar to any of my last the system won't let me use it. You can't just wander over to my desk, look around, and guess my password. Why do movies and TV think that someone can do just that to someone in a much more secure position than me and expect me to find that a believable scenario? I would believe someone trying to find a hiding spot in or near the desk concealing a post-it with the overly-complicated, nigh-unmemorable written down. OR just clicking the "forgot password" link and figuring out the answer(s) to the security question(s).
If the show/ movie is more than 10 years old they get a bit of a pass, especially if the password guessed is off of the common list from back then, such as password or secret.
Peeve 2: The portrayal of animal research
Usually this is something shown that establishes the villainous, evil corporate entity as villainous and evil.
Anyway, I've seen several shows where a variety of animals are in cages near each other in a lab. WRONG! You do not house different species together. That causes unnecessary stress, especially if there is a predator/prey relationship with any of them. Also, contamination. Speaking of contamination, you don't store animals in your lab space for exactly that reason. Oh, and that pesky care issue, there are all kinds of regulations on care and preventing cruelty in the real world.
TV tends to show science wrong, and I'm okay with technicolor science on TV, it's not nearly as dramatic looking in real life. Mostly clear liquids and hardly any fog. I only wear my lab coat when a tour comes through or if I'm cold. I wish there was more bubbling green flasks and reactions that have a little puff of smoke. Then again, wearing goggles gets old fast and I do get to play with dry ice and liquid nitrogen on occasion.