Russell Johnson & Alan Hale Jr. Were In A Western Together Before Gilligan's Island
Producer Sherwood Schwartz wasn't looking to make anyone a star when he began casting his 1960s sitcom "Gilligan's Island." The show was intended to be slapstick fun for the whole family, peppered with jokes that landed just as hard with parents as they did with their children. To get this across, he needed an ensemble that could remain in mellifluous orbit around Bob Denver's blundering Gilligan. (Denver himself was already a small screen star thanks to his portrayal of beatnik Maynard G. Krebs on "The Many Loves of Dobie Gillis.") If the actors could get away with delivering Schwartz's groan-worthy banter without evoking groans from the undemanding folks at home, they were welcome on his uncharted desert island.
This isn't to say he hired a bunch of nobodies to fill out the cast of "Gilligan's Island." Jim Backus and Natalie Schafer were established, veteran performers, while Tina Louise was viewed as a rising young talent. Viewers were familiar with their faces (and, in the case of Backus, his voice), just not to the point where they'd pop more than Denver or any of their other fellow castaways.
Two other cast members who boarded the S.S. Minnow with long oeuvres were Alan Hale Jr. and Russell Johnson. Hale was a showbiz kid who'd made good as a grown-up (he was 40 when he signed on to play the Skipper), while Johnson was in his mid-30s and starting to look more like a character actor than a potential movie star. Their career trajectories were beginning to appear pretty similar when "Gilligan's Island" came around, too, which made some kind of Hollywood sense considering that, six years prior, they'd both given supporting performances in the same ho-hum studio Western.
The Skipper and the Professor go a-foraging for yuks in the Wild West
The Western was 1955's "Many Rivers to Cross," which did not, to the best of my knowledge (or the internet's), inspire Jimmy Cliff's majestic 1969 single of the same title. The humorous oater starred Robert Taylor as dashing trapper Bushrod Gentry. And we're just going to let that name sit there for a moment.
Okay. Bushrod has an unintentional side hustle that involves saving pale-skinned damsels from the indigenous Shawnee tribespeople of Kentucky. This scenario gets turned on its head when Bushrod finds himself getting saved by the plucky lass Mary Stuart Cherne (Eleanor Parker). As she tends to his wounds, she senses a love connection. Bushrod does not. Alas, when Bushrod attempts to leave the Chernes' home, Mary has her brothers force him into a literal shotgun marriage.
As for how Hale and Johnson fit into this yuk-fest, the former plays Mary's miffed suitor Luke Radford, while the latter plays a fellow named Banks. There's no hit of marooned hilarity to come from this pair (they never interact here), but if you were to switch on this movie back in the day without paying attention to the cast list at the outset, you might get a chuckle out of seeing Hale and Johnson playing somewhat against their "Gilligan's Island" types (which Johnson would eventually find difficult to escape).
As for the quality of the film itself, you can determine that for yourself by renting it from the outlet of your choice or streaming it for free (with ads) on Tubi!