This movie uses primarily the comedy framework of an awkward situation that goes on so long that it becomes funny, so comedy mileage may vary among audience members. That being said, the antics of Chevy Chase, Steve Martin, and Martin Short are on point and the trio of SNL veterans are having a blast hamming it up. It’s a classic for its comedy, not its depth.
Closest comparison: It’s like a cross between The Magnificent Seven and Galaxy Quest.
Setting: Western
Plot: Fish out of Water
Tone: Screwball Comedy