During the opening credits, the scene in Pennsylvania Station behind Director Delbert Mann's credit, is the same shot as the last scene of the movie. If you look closely, you can even see Glenn Ford standing near the Information desk.
At the time this movie was being filmed, the demolition of the above-track-level portions of New York City's Pennsylvania Station was beginning. In the opening scene of Evie Jackson's (Geraldine Page's) arrival in New York City, you can see several panes of station windows broken and replaced with boards. By 1966, the station had been converted from its old to its new form, and the new Madison Square Garden had been added on top of it.
This plot, based on a story by Tad Mosel, was first used in Studio One in Hollywood (1948) season nine, episode thirty, "The Out-of-Towners". It debuted live on television on May 6, 1957 and starred Eileen Heckert as Evie and E.G. Marshall as Harry.
Filming concluded on November 22, 1963, the day President John Fitzgerald Kennedy was assassinated.
Amongst the people being paged in the hotel lobby was Dorothy Aldrin, who was the Script Supervisor. There was also a page for "Roy Fitzgerald", which was Rock Hudson's real name; Delbert Mann had recently directed him in "Lover Come Back" and "A Gathering of Eagles".