Jacqueline Bisset took over the role of Laura from Charlotte Rampling, who bowed out because of pregnancy. [VARIETY, Mar 15, 1972]
The opening scene where where Webster quits his job and drives away is actually set at the Houston Space Center, NASA.
At the cocktail party, Henderling introduces Webster to "Mr. & Mrs. Lanier". That was future Houston mayor Bob Lanier (aka Robert Clayton Lanier).
The Houston Post is no longer in business having lost the newspaper war to the Houston Chronicle. The Post was the morning newspaper, and the Chronicle the evening newspaper in Houston where this film is set.
When Jill Clayburgh gets into the back of the taxi after visiting with Warren Oates outside the Alley Theatre, she says "Rice Hotel, please." The Rice Hotel is only two blocks up the street from where she was and just outside the camera shot.