When Ann gets out of the cab in front of the Grenville house for the first time, she is a wearing mink coat. She takes out her compact to look at her face. When the shot switches to inside the house, the butler opens the door and Ann is standing there, with the compact in her hand, but the coat is now draped over her shoulders.
It's supposed to be 1944, but the first exterior view of the Astor Hotel shows two adjacent film theatres, the Astor and the Capitol, playing We Were Strangers (1949) and Scene of the Crime (1949), both of which premiered in New York City in July 1949. A few minutes later, another view shows the Astor playing Melody Time (1948), and the Criterion across the street playing Easter Parade (1948), both of which premiered in June 1948.
While opening scenes of movie are set prior to end of WWII (1945), stock footage features a sign for Broadway production of A Streetcar Named Desire which didn't open until 1947.
In 1955, Ann makes an operator-assisted long distance call from England to United States and is connected to her party in less than ten seconds - an impossibility even now, with direct dialing.
Equipment shadow swoops over set when William's mother visits Ann in hospital room.