Gus is a film about a football-kicking mule ("Gus") and his trainer "Andy" (Gary Grimes).
The film opens with a soccer game, and the Petrovic family watching their son Stepjan win the soccer game. Andy Petrovic works on his farm in Yugoslavia, and can't play soccer at all. A soccer ball is behind his mule, Gus. After saying that he never wants to see a soccer ball again, Gus kicks the soccer ball and Andy tries it with him and he says, "Oyage!" and Gus kicks the ball.
Meanwhile, the California Atoms are a team that cannot do anything right. Debbie Kovac, a woman with Yugoslavian parents gets the Yugoslavian papers, and once Hank Cooper and Coach Venner find out about Gus, they want him over. So with that, Andy and Gus fly over to California and Gus' kicking of the football gets them to agree to keep him in.
The film did well and was released on home video in 1981. The movie is remembered for two sequences involving a hotel and a supermarket.
This is the only one of their five films together where Don Knotts and Tim Conway do not share any scenes.
Johnny Unitas appears as a commentator with Bob Crane supplying the play-by-play during the football broadcasts. Dick Enberg did the play-by-play for the local games.
The name "Hank Cooper" was later used in the Disney film The Love Bug as the name of the mechanic who meets Herbie (played by Bruce Campbell). Don Knotts co-starred with Dean Jones in the film Herbie Goes to Monte Carlo.