Renée Zellweger's costumes were created by the Montreal-based clothing company Le Chateau.
Cartoon animator/MAD artist Richard Williams made a fake MAD cover involving 'Alfred E. Neuman' as Barbara holding her book. MAD commented on its cameo in the movie as a sure-fire kiss of death for a movie.
The extra scene at the end with Ewan McGregor and Renée Zellweger singing a duet was filmed at the insistence of the actors. They said that with both of them having been in musicals previously (McGregor in Moulin Rouge! (2001) and Zellweger in Chicago (2002)) that it would be a sin not to.
Barbara's long monologue, which lasts 3:02 in a single, unbroken shot, took six takes to get right.
Peyton Reed cites the popular auctioning website eBay as a good source for finding period costumes and props to use in the film.
55 sets were built in four sound stages.
Everything the characters wore, literally from head to feet, was custom-made for them.
The spilt-screen telephone calls scenes are direct homages to 1950s/'60s screwball comedies.
To create this movie's vivid, stylized appearance, cinematographer Jeff Cronenweth digitally color-timed the movie to simulate the appearance of three-strip Technicolor.
The front cover of the MAD magazine was fake, but the back cover was from a real issue from the late-1960s.
Average Shot Length = ~5 seconds. Median Shot Length = ~4.5 seconds.
During the dating montage, one of the scenes in the background is of a man playing bongo drums. This footage is taken from the scene in Pillow Talk (1959) when Doris Day's and Rock Hudson's characters first meet.
There are several pieces of dialogue that mention "Nazi rocket scientists." This is a reference to Operation Paper Clip, the post-World War 2 U.S. Government project that transferred the Nazi scientists who developed the V-2 rockets that bombed London to the U.S. to work on the beginnings of the U.S. Space Program, largely in Huntsville, Alabama. The most famous of these scientists, Wernher Von Braun, had been the technical director of a Nazi rocket factory that was staffed by slave labor from the nearby Mittelbau-Dora Concentration Camp. Von Braun was essential in the creation of the Redstone missile, the basis for the U.S. Missile program, and the Saturn V rocket, the basis of the Apollo program, which sent American astronauts to the moon.