My Cousin Vinny is actually really good, not only because it is an entertaining movie, but also because it is actually one of the more accurate portrayals of how lawyers actually operate in a court of law.
There is a youtube channel out there where a lawyer takes a look at various movies / tv shows involving court rooms and he grades them on accuracy with regards to what you can and can't get away with in an actual court and if their legal arguments pass muster.
You are not allowed to walk up directly in front of the jury and talk to them.
You generally are not allowed to approach and directly talk to the witnesses on the stand.
Alot of arguments in movies are stupid and would have legitimate sustainable objections.
For example, a few good men, while a fantastic movie, is atrociously bad with regards to Tom Cruise's behavior. He would have been thrown out of court long before getting to the "You can't handle the truth" moment.
My Cousin Vinny though is actually really good. While the scene where he gets Marissa Tomei to give her expert opinion is great, the important scene is the one right after that where he brings the opposition's car expert back to the stand to refute the Marissa's testimony (which he can't).
If people are truly interested, I can link the lawyer's review of that movie.