Chevy Chase's Epic Christmas Vacation Rant Is In The Original Script

Scripts are great, but a surprising number of the best moments in movie history were improvised. John Hughes' scripts, however, didn't particularly require that much in the way of improvisation, with most of the hilarious dialogue already written out in the script. 

According to the John Hughes biography "John Hughes: A Life in Film," Hughes liked to allow his actors to ad-lib dialogue, but when circumstances required the actors to stop ad-libbing, the movies still came out great. In "Planes, Trains, and Automobiles," which Hughes both wrote and directed, Steve Martin and John Candy found improvising their lines to be too difficult in the cold weather as the camera crew had to keep shifting every time an actor ad-libbed a line. "It was getting ridiculous, covering everything fifty times if we ad-libbed ... It was literally freezing," Martin said. "I was in a topcoat and John [Candy] a parka. All this ad-libbing was making the camera crew swing around us in the camera car again and again [to cover the shots]. Candy and I finally agreed not to ad-lib anymore" (via SlashFilm). Despite halting the pair's ad-libs, "Planes, Trains, and Automobiles" remains a classic holiday film.

"National Lampoon's Christmas Vacation" is one of the films that Hughes wrote but didn't direct, and surprisingly little of it is improvised. According to director Jeremiah S. Chechik, the dialogue that was in the script was so good there was very little need for ad-libbing.

In an interview with Flashback Files, "Christmas Vacation" director Jeremiah S. Chechik was asked how much of the famous holiday movie was improvised, and he explained that very little of it was since the script was already so funny. Chechik also mentioned that much of the dialogue had to be written on cue cards. 

In an interview with The Dinner Party Download, Beverly D'Angelo explained further how the epic rant that Clark goes on after finding out he wasn't getting his Christmas bonus was filmed so that Chevy Chase could remember his lines. "Well, when you run a scene, you have to block it. You are assigned a place to stand for camera placement and all that kind of stuff. But this particular scene, it was blocked in a way that would allow each of us to have around our necks a piece of rope that was attached to a big cue card." According to D'Angelo, if you watch the famous scene, you can see Chase's eyes moving from one person to the next during his speech because the other actors were all wearing cue cards that are not necessarily in order.

Hats Off Entertainment even did a breakdown of the famous scene on YouTube which shows the finished scene compared to the original script, and there are very few differences between the script and the finished product. Even the famous ending line, "Where's the Tylenol?" was written in the dialogue.