Though I am a big fan of Mel Brooks, I think that one reason this film succeeds so well is that Robert Aldrich directed it instead of Brooks. In other words, it is essentially a dramatic western that is filled to the brim with comedy -- instead of the other way around. Aldrich had previously directed serious epic westerns, and he became famous in the sixties for directing What Ever Happened to Baby Jane, Hush... Hush, Sweet Charlotte, The Flight of the Phoenix, and The Dirty Dozen. These films, as well as his classic The Longest Yard, showed how infusing humor into serious drama can make plots more interesting and characters more human and sympathetic.
Frank DeVol provided the music ... and you can see him in the part of the old time piano player. DeVol had provided music for a number of Aldrich films, including the five films mentioned in the previous paragraph. He was famous for his comic scores (e.g., Pillow Talk, Cat Ballou, and The Trouble with Angels) and his music for TV series (e.g., My Three Sons, The Brady Bunch, McCloud, and the Love Boat).
Another gem in this film is Harrison Ford -- in a role that seems so second-nature to him, but showcases his versatility. His character is not that much different from Hans Solo. (Star Wars appeared in 1977 and Empire Strikes Back appeared in 1980, while The Frisco Kid came out in 1979.) In fact, it seemed emblematic of the movies in the sixties and seventies that some of our big screen heroes were selfish rogues with a heart of gold. Think of Butch Cassidy and the Sundance Kid, which came out in 1969.
The executive producer was Hawk Koch, whose father, Howard W. Koch was a Hollywood icon, having produced scores of films, including The Manchurian Candidate and The Odd Couple. This was one of Hawk Koch's first jobs, and he has now been the executive producer of over twenty outstanding features, including Mike Myers' Wayne's World and -- another great comedy exploring religious belief -- Keeping the Faith, with Ben Stiller and Edward Norton.
Finally, because the DVD is not yet available, here's a gem that was not included in the IMDb Memorable Quotes section, though I have edited it to avoid giving too much away for those who haven't seen the film yet:
"Chief Gray Cloud: Yes or no, can your God make rain?"
"Chief Gray Cloud: But he doesn't?"
"Avram: That's right."
"Chief Gray Cloud: Why?"
"Avram: Because that's not his department!"
* * *
"Avram: ... He gives us strength when we're suffering! He gives us compassion when all that we feel is hatred! He gives us courage when we're searching around blindly like little mice in the darkness! ... "
HOW TRUE! Whether you identify with Gene Wilder's Rabbi or with Harrison Ford's Rogue, this film is filled with valuable lessons. The world is unpredictable. Sometimes we suffer. And sometimes we find strength, courage, compassion, ... and humor to deal with it all.