To create the effect of a vast sea of faces laboring grimly and impersonally at their desks in the huge insurance company office, designers Alexandre Trauner and Edward G. Boyle devised an interesting technique. Full-sized actors sat at the desks in the front and children dressed in suits were used at tiny desks toward the rear, followed by even smaller desks with cut-out figures operated by wires. It gave the effect of a much larger space than could have been achieved in the limited studio space.

For this film, Billy Wilder became the first person to win the Academy Awards for Best Picture, Best Director and Best Screenplay.

Billy Wilder originally thought of the idea for the film after seeing Brief Encounter (1945) and wondering about the plight of a character unseen in that film -- the person who lends his apartment for an extramarital tryst. Shirley MacLaine was only given forty pages of the script because Wilder didn't want her to know how the story would turn out. She thought it was because the script wasn't finished.

Jack Lemmon said he learned much about filmmaking from Billy Wilder, particularly the director's use of "hooks," bits of business the audience remembers long after they've forgotten other aspects of the movie. One such hook was the passing of the key to Baxter's apartment. Lemmon said for years after the picture's release, people would come up to him and say, "Hey, Jack, can I have the key?"

The office Christmas party scene was actually filmed on December 23, 1959, so as to catch everybody in the proper holiday mood. Billy Wilder filmed almost all of it on the first take, stating to an observer, "I wish it were always this easy. Today, I can just shout 'action' and stand back."

Continuity

Baxter gives Fran coffee to drink. The coffee is freshly made and so it's boiling hot, but she drinks it quickly, as if it had been sitting around for some time.

After Bud finds out that Ms. Kubelik was with Mr. Sheldrake, he leaves wearing his new hat, leaving his old hat behind. Later that night when he arrives home with the woman from the bar, his old hat is on the hat rack on the wall.

The frozen daiquiri in the cocktail lounge melts, reforms, and melts again. Also, the straw in it disappears and reappears.

After Baxter gets home for the first time, he cleans up by placing a large waste bucket of empty liquor bottles outside his apartment door. An hour later when he has to vacate the apartment for one of the other men, the waste bucket full of bottles is gone. There was no one around to carry his bottles away at that time of night.

The shaving cream on Baxter's faces changes between the bathroom and bedroom.



Factual errors

After Kirkeby leaves, Baxter goes to the kitchen, lights his oven, removes a TV dinner from the refrigerator, and puts it in the oven without bothering to set a temperature on the dial. Less than two minutes later, after taking his empty bottles to the hallway and speaking to the doctor, he returns to the kitchen and removes the TV dinner from the oven. Most TV dinners require at least thirty minutes in the oven at a set temperature. Even a modern microwave oven is unlikely to thoroughly cook a TV dinner in less than two minutes.

Baxter finds a piece of spaghetti on the tennis racket he had used earlier in the picture to strain a pot of pasta. While thinking he twirls the noodle around his finger. Pasta left out like that would have stiffened up. And he never would have been able to spin it. The strand of spaghetti could have come from a meal he just cooked, not from the one he fixed Fran a week earlier.

When Miss Olsen picks up the extension after being fired, Sheldrake is heard completing dialing his call to Baxter. A rotary dialer will not work when an extension is off the hook.

The movie is set in 1959, a year when Christmas Day (December 25th) landed on a Friday. Yet the office is shown fully staffed the next day, which should be empty over the weekend.

C. C. Baxter suggests 5 feet 6.5 inches as the average height of a New Yorker, but given the large percentage of the 8 million-plus New Yorkers he cites (and which figure he uses as a multiplier) who are children, this is undoubtedly too high.



Revealing mistakes

When Dr. Dreyfus calls to his wife that Baxter is at it again, then slams his apartment door shut, the wall shakes noticeably, revealing it to be a set, rather than a real wall.



Crew or equipment visible

When Fran cries in front of the mantel, someone can be seen reflected in the TV screen sitting and watching the scene play out.



Errors in geography

The layout of Baxter's apartment makes no sense, especially in relation to Dr. Dreyfus's apartment. Dreyfus lives next to Baxter, which means their walls should be adjoining the full length of both flats. However, from inside Baxter's living room, one can see windows in both his kitchen and bedroom facing directly where the Dreyfus apartment should be (and there would likely be a window in the bathroom between the kitchen and bedroom). Dreyfus's apartment would have to veer immediately off to the extreme right when one enters it and be no more than a couple of inches wide in order to allow the kind of set-up seen in Baxter's apartment. This is clearly unrealistic, if not downright impossible.

During the opening pan of the New York skyline with the United Nations Building in the foreground, the shot is actually a "mirror-image" of the actual scene.



Plot holes

In the opening sequence, Jack Lemmon's character narrates that his name is C.C. Baxter, "'...C' for Calvin, 'C' for Clifford... But most people call me 'Bud'". However, throughout the movie, no one calls him "Bud". Miss Kubelik calls him "Mister Baxter", Mr. Sheldrake calls him "Baxter" and the other executives call him "Buddy Boy".

Baxter comes back to the apartment as his landlady tells him she smells gas. He also smells gas when he gets inside but when he goes into the kitchen he does nothing about it.



Boom mic visible

(Widescreen version only) The shadow of a boom mic is visible in the upper left portion of the screen as C. C. Baxter is rushing to open his apartment door after being alerted to an odor of gas by his landlady.



Character error

Mrs. Lieberman is in a panic, telling Baxter that she smells gas coming from his apartment. It is her building and a potentially dangerous situation, perhaps requiring the fire department or an ambulance, but she immediately loses interest in the problem after informing him and simply goes back downstairs.

When Fran is in Jack Baxter's office during the Christmas party, she is wearing lipstick and and mascara. After Baxter puts his hat on and asks how he looks, she isn't wearing any makeup.

Fran buys a record album recorded by the small combo that performs in the Chinese restaurant she patronizes, but when the record is played in Baxter's apartment, the tunes are lush orchestral arrangements, nothing like the lounge music heard in the caf?.

When Kirkeby returns to the apartment to look for the galoshes left behind by Sylvia, he first looks behind the chair to the right of the fireplace, then he goes to the left of the fireplace to look behind another chair, then he returns to the right of the fireplace, where he picks up the galoshes behind the chair where he already had looked when he first came in.

When telling the story of his attempted suicide, C. C. Baxter pantomimes loading a revolver, even though he has specified (and it is later seen) that the gun he used was an automatic.