Although set in the early 1950s, just after the Korean War, the U.S. flags in the movie have 50 stars at a time when the United States had only 48 states. In addition, the large U.S. flag displayed against the wall at the dance was backward, with the field of stars on the right. When displayed vertically, the flag should always have the stars at the upper left.
In an early scene in the film, the RCA Dome (at the time of filming the home of the Colts, but has since been demolished) is clearly visible behind Union Station.
One of the games that Buddy throws out is CAREERS, which was first published in 1955; the film is set in 1954.
Set in 1954, the film opens with a 1957 hit song.
When Sonny bangs his head on the floor after his failed attempt to have sex with Gale, the sounds of the thumps are not in sync with the picture.