There's a Mandela effect about Cast Away(2000) that I will spoiler alert in the body to ask about.

Perhaps you are thinking of Swiss army man which has several of those scenes. https://m.imdb.com/title/tt4034354/

I'm 90% sure that he goes to the top of the mountain to get the rope that he used because he already used up all of the plant he needed and still came up short.

They never show him doing it, they only show him pulling the wooden dummy up past the broken branch, then he tells his friend about it explicitly after being rescued.