This is a list of things in films that bug me because they're unrealistic. I made it because I felt like it.
Driving without keeping one's eyes on the road. You'd think a good actor would know that when people drive, they generally keep looking ahead of them. If they do look elsewhere, they do so for a second or two, tops (or they crash). So how do even the best actors get away with taking their eyes off the often-busy road for ten seconds or more at a time to have a conversation?
Drinking out of cups that are clearly empty. For some reason, this happens in Dexter all the time. Not surprising, perhaps, since donuts and coffee are two of the biggest recurring characters in the show. But it is obvious to me when someone is drinking out of an empty cup. Especially when it's shop-bought coffee that would clearly burn your tongue off at the roots if you drank it that quickly.
Picking up boxes, bags and packages that are clearly empty. Newsflash to props guy: We can tell that crate that guy just picked up is made of fibreglass and contains a nothing but a handful of packing peanuts.
People in meetings and church services responding in unison. Maybe it's just me, because I endured all of my adolescence in Pentecostal church services, but it irritates me when everyone responds to a preacher or evangelist with a perfectly unison "Amen!". Real born-again services are a little, and sometimes a hell of a lot less coordinated.
I may add to this list occasionally as other bits of random Hollywood fakery grate against me.