How about when someone is supposed to be establishing their bona fides as the “Car Person” in a movie so they use some technical jargon or slang to describe a car or component that is just completely wrong. For a normal car enthusiast it only makes it painfully obvious that they have no idea what the hell they are talking about.

One of the examples that still sticks out to me was from the original Transformers movie when BumbleBee “breaks down” and she opens the hood and goes “... you’ve got a high rise double pump carburetor.” At which point they show a nice close up of the engine... and it’s some sort of quad two barrel side draft carb, or ITB fuel injection setup, with velocity stacks.

The first time I watched that movie I facepalmed so hard when she said that I nearly injured myself. I am not going to pretend that I know exactly what that setup was... but I knew without a split second of hesitation what it wasn’t.