I find it ridiculous how often media characters break the gun safety laws. I only used a gun in one week in my life, and even I know the basics.
Grimm: Here's the gun, Sam. Just point it at the right people.
Sam: Oh, I will....(immediately swings it, facing her head for a solid second before leaving)
1. ALWAYS keep the gun pointed in a safe direction.
Mafia 2, when Joe accidentally shoots a barkeep
2. ALWAYS keep your finger off the trigger until ready to shoot. (To be fair, Joe was drunk)
etc etc
Also, there's the misconception that you can shoot someone in the leg or something to avoid killing them. Your leg has plenty of arteries and nerves too, and people can potentially have crippling life-changing injuries or even die from a .22 shot to the leg. It's less common, sure, but the end rule: A gun is a weapon you only use if you intend to KILL your target.
Then there's the ignorance of penetration (ie, no one can really take cover during an indoor firefight) but things would be much less exciting without that so I let it slide.