Ralph Bellamy got a good taste of Leo McCarey's working style very early on. He was simply told to show up on the set the following Monday for filming, with no script, no dialogue, or even a hint about his upcoming scene. So he went to see the director, but received no help at all from the perpetually upbeat McCarey. "He just joshed and said not to worry, we'd have lots of fun but there wasn't any script," Bellamy wrote years later. The actor showed up on set for the first day of production to find Irene Dunne at a piano. (McCarey almost always kept a piano on his sets, and he would often sit playing while he thought up a new scene or piece of business he wanted his actors to try.) Dunne was pecking away at the melody to "Home on the Range," and McCarey asked Bellamy if he could sing. "Can't get from one note to the other," the actor replied. "Great!" McCarey said and ordered the cameras to roll while Dunne played and Bellamy sang for all he was worth. When they finished the song, they heard no "Cut." Looking over, they found McCarey by the camera, doubled over with laughter. Finally he said, "Print it!" The scene ended up in the finished picture. That was the way McCarey worked, and Bellamy had to get used to it quickly.
Irene Dunne later recalled the scene where she pretends to be Cary Grant's ill-bred nightclub performer sister, which was written over a weekend and handed to her on the morning she was scheduled to film it. She was supposed to do a burlesque bump in the middle of her musical number in that scene, a move she was never able to do. McCarey told her to just say, "Never could do that" when she got to that moment. She did, it stayed in the film, and Dunne found it "a choice comic bit."
The dog playing Mr. Smith was named Skippy, and was most popular for its role in The Thin Man (1934) movie & its sequel, as Asta. On those movies, he was notorious for trying to bite the actors. Even in this film, there's a scene where Cary Grant is trying to play with the dog, and the dog very obviously snaps and growls at him.
When Leo McCarey received his Best Director Oscar for the film, he reportedly said that he got it for the wrong film, a clear reference to his fondness for Make Way for Tomorrow (1937), which he made the same year.
Leo McCarey's means of maintaining control over the picture was to shoot very little coverage of each scene and basically do all his editing in the camera. That way, there was very little leeway in how the footage could be edited other than the way he intended.
While Cary Grant was initially working with Leo McCarey, he was unaware that McCarey was deliberately creating nervous tension in the actor, in order to enhance his performance. By keeping the cast slightly off balance, the director was building scenes from spontaneous moments between his actors. Giving the barest outlines of a scene, he would have his actors try something on their feet. For instance, in one rehearsal, he told Irene Dunne to simply open the door of her apartment and say, "Well, if it isn't my ex." He told Grant to answer with whatever came into his head. Grant replied, "The judge says this is my day to see the dog." McCarey then built the scene around that moment. The line, and the subsequent scene, stayed in the picture.
Leo McCarey's process enabled him to keep control over the tone of the film, throwing his cast off balance so they were not able to arrive on set with memorized lines, psychoanalyzed characterizations, and performances already frozen in their minds.
The Awful Truth (1937)'s release date, Thursday, October 21st, 1937, was 168 days (24 weeks exactly) after the German dirigible, the Hindenburg, exploded in Lakehearst, New Jersey, on Thursday, May 6th, 1937.
The trivia item below may give away important plot points.
According to Irene Dunne, Leo McCarey was unsure how to end the picture until a member of the crew came up with the idea of having the male figure on the clock follow the female figure back through her door, a perfect (and censor-friendly) substitute for showing Cary Grant climbing into bed with Dunne.