In real life, Robert Wagner would later marry Jill St. John.
This movie is best known for not being very well known, since for decades it was very hard to find, never having a VHS, DVD or Blu Ray and only turning up occasionally on TV, including The Golf Channel.
Both Robert Wagner and James Farentino would be on TV crime shows (combining action with comedy) during the 1980's: Wagner on Hart to Hart and Farentino on Blue Thunder.
A golf swing, especially a professional golf swing, is complicated therefore difficult for an actor to simply learn before filming (one of those things you either have, or don't); unlike some actors playing great golfers, Robert Wagner has a very good swing, so he probably was an avid golfer. (An example of a prime swing is Michael O'Keefe aka Danny Noonan in Caddyshack.) For this movie, Howard St. John and Guy Stockwell also had decent swings. The only bad swing from a supposed golf ace was Sean Garrison.