In his autobiography, The Name's Above the Title, Frank Capra said that until It Happened One Night drama had four stock characters, the hero, the heroine, the comedian, and the villain.
What Capra did and you might notice he followed that in a whole lot of his films, the characters of hero and comedian are combined. Not completely though because Claudette Colbert gets a few laughs herself, especially with that system all her own. But in doing what he did for Clark Gable's character, Capra created a whole new type of screen comedy, the classic screwball comedy and It Happened One Night surely set the mold.
Capra's autobiography told the story of the making of It Happened One Night which in itself could be a movie. Capra worked for Columbia Pictures which at that time was a minor studio, along the lines of Republic or Monogram. As Capra tells it he had a vision about this story that Samuel Hopkins Adams wrote and persuaded Harry Cohn to buy it.
Capra also had a stroke of good luck. Adolph Zukor at Paramount and Louis B. Mayer at MGM were looking to punish a couple of recalcitrant stars, Claudette Colbert and Clark Gable. The idea was to show these two what it was like to work in a small budget studio without all the perks of Paramount and MGM. In fact the description of Gable arriving to work at Columbia that first day, drunk as a skunk, is priceless. Capra dressed him down good and said that to his credit Gable came to work afterwards and couldn't have been more cooperative.
At some point Harry Cohn at Columbia was convinced that maybe Capra had something. He had in fact delivered for Columbia the previous year with Lady for a Day. So the publicity drums were beat.
The rest as they say is history. It Happened One Night won the first Oscar grand slam, Best Picture, Best Director, Best Actor, and Best Actress. It won the first Oscars Columbia Pictures ever got and lifted it right into the ranks of the major studios. And it set the standard for screwball comedy.
The film could never have gotten off the ground were it not for the chemistry of Gable and Colbert. They're together for most of the film so if it doesn't click between the two of them, you have people walking out in droves. Colbert had already played a wide variety of parts at Paramount, ranging from Poppaea and Cleopatra to comedies with Maurice Chevalier like The Big Pond. Gable had played a whole lot of tough guys on both sides of the law at MGM. It Happened One Night showed he had some real comic talent, a flair MGM exploited in his roles from then on in.
Gable and Colbert did only one other film together, Boom Town for MGM. You can't get much more different than those two films. Boom Town had a huge MGM budget, Spencer Tracy and Hedy Lamarr as well, and a lot of special effects involving the oil industry and hazards therein. It's also a great film, but it's not a classic like It Happened One Night.