When Vinny is trying to convince Bill to allow him to represent him, he performs a card trick. Lynn talks about the authenticity of the scene in the DVD commentary, explaining that it was imperative for him for the trick to be real.
So, Pesci had to actually learn how to do the trick! And he did it brilliantly.
The Prison Guards Used Are Not Actors
The prison guards which appear in the film are actual prison guards. Real prisoners were also used as extras on two occasions, once shouting in the background as Stan and Bill are being led into the prison, and also for a short scene in which the two play basketball in their exercise time.
Lynn says in the DVD commentary, “The prisoners were all extremely cooperative and did exactly what we asked. I don’t know what incentives or threats were made in order to achieve that.”
The Scene in Which Vinny and Stan Misunderstand Each Other Was Cut from the Script
This hilarious scene, in which Vinny and Stan meet for the first time, appeared in the script which Lynn received, but was cut from the shooting script. All parties involved felt like the scene had to be added back in, and it ended up getting some of the biggest laughs. The scene, which took place inside Stan and Bill’s cell, could not have happened in reality because any interaction between defendants and their attorneys could only take place in an interview room.
The filmmakers discussed this point and tried to solve it a little by showing Vinny giving the guard money. Lynn has said that making the scene accurate would have caused them to lose that brilliantly funny scene, so they decided not to use it and hoped nobody would notice the small inaccuracy. And nobody ever did.
Bill’s Mother’s Scenes Were Dropped in Editing
While they were getting ready to shoot the film, someone at the studio brought up a big hole in the plot, how is it that Bill’s Italian mother never shows up to support her son who is going on trial. “Well, that was a tough question, because the answer is, Mother ought to have been there,” Lynn said in the DVD commentary. But then he went on to say that it would've been a problem because the script was already too long.
Instead, they added some scenes where Bill's mother suffers from a heart attack right after Vinny goes to Alabama. But when editing, they realized the scenes were going to ruin the film's continuity, so they decided to cut them out.
A Live Screech Owl Was Used to Create One Unforgettable Scene
One of the movie’s most memorable running gags is that Vinny can never wake up naturally and is always startled awake by something, be it a steam whistle, boisterous pigs, and even a screech owl. Lynn talks about their decision to use a real screech owl in the DVD commentary, which he later admits was probably a ridiculous thing to do. The owl's behavior was so perfect that people thought it was fake. "It screeched, it looked back at Vinny, and then it looked back at the camera and screeched again. We got amazingly lucky with that screech owl.”, said Lynn.
The screeches were actually added in later. The filmmakers used a special trick to get the owl to open its mouth at the right time: “We discovered that if you put a little bit of meat into its beak, it half swallows [it] and then, approximately three seconds later, opens its beak as the meat goes down,” Lynn said. “So we fed it a little bit of beef just before the camera starting turning so that for its first screech, which is added afterwards, his beak opened at the right moment. Everything else he did in that scene was pure luck!"