Jacqueline Bisset took over the role of Laura from Charlotte Rampling, who bowed out because of pregnancy. [VARIETY, Mar 15, 1972]
At the cocktail party, Henderling introduces Webster to "Mr. & Mrs. Lanier". That was future Houston mayor Bob Lanier (aka Robert Clayton Lanier).
Walter Hill's screenplay, based on the novel by Terrence Lore Smith, shifts the plot locale from Chicago to Houston and completely leaves out the relationship development between Webster/Dave and Dave/Jackie (called Lina in the book) and the gradual physical change in Webster (in the book, he starts out as balding with a broken nose and scars from college football, but has hair grafts, dental work, rhinoplasty and scar removal, whereas in the film he is "pretty" from start to finish).
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.
The opening scene where where Webster quits his job and drives away is actually set at the Houston Space Center, NASA.