Billy Wilder preferred shooting in black and white, but Marilyn Monroe's contract with Fox called for all of her movies to be shot in color. Monroe always thought that she looked far more attractive and glamorous in color than in black and white.

Marilyn Monroe's iconic white dress set a record when it was auctioned for $4.6 million in June 2011 (rising to $5.5 million after taxes and fees were included), quintupling the previous record for a movie costume ($923,000 for Audrey Hepburn's "little black dress" from Breakfast at Tiffany's (1961)).

The Seven Year Itch is one of the few films that utilize footage of New York City's original Pennsylvania Station - opened in 1910 and torn down in 1963. The Beaux-Arts style station - considered a masterpiece of architecture - was modeled after the great, natural light stations of Paris, and a brief glimpse of its glass ceiling can be seen when Richard takes his wife and son to catch their train toward the start of the film. The destruction of the station - and the subsequent shock of a previously ambivalent city - is widely credited with jump-starting the historic landmark preservation movement.

While many actors were considered for the role of Richard Sherman (played by Tom Ewell), no one but Marilyn Monroe was considered for the role of The Girl.

After seeing Walter Matthau's screen-test in the part of Richard Sherman, Billy Wilder believed he had found his leading man. However, 20th Century-Fox was unwilling to take the risk on a newcomer. That's when Wilder next turned his sights on the actor who had originated the role on Broadway, Tom Ewell - who is inexplicably billed as "Tommy Ewell" in the opening credits.

Continuity

When Richard is talking on the phone, he moves to the porch during his phone call. At first, the cord of the phone is seen coming around the corner through the doorway, but later disappears and eventually reappears.

The second time Richard slips on a roller skate, it bends, but when he picks it up again, it appears unbent.

In the scene where Richard opens the door for The Girl, at the time she forgot her front door keys, he gets out of the apartment to talk to her and look at her going upstairs. When he gets out the lights are on, but when he come back after he hurt his neck, the lights are off.

When Sherman gets his finger stuck in the champagne bottle it appears 1/4 full. After he gets his finger out and the girl pours a glass it is about 3/4 full.

Miss Morris entering Sherman's office where he has the paddle. Enter shot has her with poster in left hand, note pad in right. Going through door poster in right hand and she places notepad carried in left hand on desk.



Incorrectly regarded as goofs

When Helen shoots Richard in his fantasy, seven shots are heard although the gun is a six-shot revolver. Moreover, she enters the apartment by emptying the gun into the front door, yet she doesn't reload. Some of the bullet holes disappear between shots. Since this is Richard's fantasy, it need not conform to reality.

When Richard is reading the statistics in the doctor's manuscript, a stat is given that the seven year itch affects 84% of men in their 7th year of marriage. The next stat says that this number increases to 92% in the summertime. However, this makes no sense. If the stat is that 84% of men in their 7th year of marriage get the itch, then how can it change depending on the season? The logic does not follow.



Revealing mistakes

When Richard sets the coffee pot on the stove and turns on the gas, there is no flame, yet the pot is percolating when he returns to the kitchen minutes later.



Miscellaneous

The Roller Skate could not roll out to trip up Mr. Sherman. The Skate rolls out on a level floor carpet where Sherman steps on it and falls spilling the ice. Unless there was a Poltergeist to push the skate out to trip up Sherman, there was no logic & reasoning for the skate to move. It made more sense to just have the skate there than roll it out on camera violating all laws of physics.

The Ice Bucket was in the refrigerator not freezer slowly melting. From when he was drinking his "raspberry" soda from the bottle to drinking his liquor 'neat' without ice to The Girl (aka, Marilyn Monroe) going to get her Champagne Bottle, Sherman had not prepared a bucket of ice. Yet, he rushed into the kitchen for a bucket of ice in the Fridge, not Freezer.



Errors in geography

Helen and Ricky supposedly summer at a lakeside resort in Ogunquit, Maine, but there are no lakes in Ogunquit, which is a seaside town. And when Sherman calls, he mispronounces the town as "Ogonquit."



Character error

Both Richard and his boss, who are in the book publishing industry, refer to "The Portrait of Dorian Gray". The title of the Oscar Wilde novel is "The Picture of Dorian Gray".

Richard explains that his finger is stuck in the Champagne bottle because the bubbles create a vacuum. Bubbles wouldn't create a vacuum and would, in fact, push his finger out of the bottle.