The telephone operator asks for an additional $2.00 for a 3-minute continuation of the long distance call between Johnny and Molly. This equates to about $34.50 in 2017, which accurately depicts the cost of long distance telephone calls at the time. They were expensive and rare for the average citizen.
The house where Ken (Richard Egan) and Sylvia (Dorothy McGuire) live toward the end of the film is an actual private residence that was built by Frank Lloyd Wright in 1948. It is called the Clinton-Walker House, still stands today on Scenic Road in Carmel-by-the-Sea, and is a prime feature in local tours.
The role of Molly was offered to Natalie Wood, but she turned it down. She would later say that she regretted doing so.
Richard Egan's (Ken's) impassioned speech to his wife about her disgraceful bigotry was so powerful that an entire packed audience at Radio City Music Hall gave it an immediate standing ovation.
The events in the original novel take place over about 20 years, including a period where Ken buys a Florida motel and asks Bart and Sylvia to run it in the wintertime, putting them back on solid financial footing. The movie compresses events to a single year.