Factual error: A hard pack of Winston cigarettes is shown, but these were not available in 1953.
Factual error: When we hear Doris Day singing "Secret Love" the record we see on the turntable has an RCA Victor label visible/readable. Doris Day songs were released on Columbia Records.
Factual error: When Julia Roberts and her roommate are in their living room and "I Love Lucy" comes on the TV, the opening theme song is accompanied by the traditional heart with "I Love Lucy" written on it. However, this movie takes place in 1953-1954, and that opening for the show wasn't used until the show was put in syndication many years later. During the show's primary run, cartoon characters of Lucy and Ricky opened the show. (00:13:50)
Factual error: In the scene with the big band, the band is playing a tune in which the trumpets play the melody with a muted sound (this is kind of a "metallic" sound) yet the trumpeters don't have any mutes in their horns. They would have to be awfully good players to be able to make their trumpets sound like they are using metal mutes if there were none available. This is basically an impossibility.
Factual error: The Waterford Castlemaine crystal pattern used for the etiquette lesson, and later in the house Julia Roberts lived in, did not exist in 1953. It was introduced in 1986. (00:27:50)
Factual error: Joan gets accepted to Yale school of law in 1954, but Yale didn't accept women students until 1969.
Answer: The colour change every year and the number is the year they finish (Joan's hat says 54 and their last year is 1954 as Nancy says around new year.)