On the map Russia's Baltic seaport is named "St. Petersburg." From 1924 to 1991, the city's name was "Leningrad."
The copy of the script for Marnie (1964) presented to Grace Kelly lists Jay Presson Allen as the screenwriter. The script for "Marnie" actually offered to her was an earlier draft by Evan Hunter. Allen came onto the project later, after Kelly turned it down and Tippi Hedren was cast as Marnie.
If both countries (Monaco and France) speak French, why, in English, just French characters had accent?
Princess Grace remarks "Oh, but colonialism is so last century." This idiomatic expression ("that fashion is so last year") didn't arise until the last decade or so, and certainly wasn't used in the 1960's.
The map with "New Monaco" was written in English (and not in French).
Patrons to the Red Cross Ball shout "Bravo" after the aria sung by Maria Callas. The correct exclamation, not pretentious in any way, is the singular feminine "Brava."
From limited research, it seems Grace Kelly was right handed. Nicole Kidman is left handed. When Nicole was autographing Kelly's college program in the movie, she was signing with her left hand.