What's the deal with the horse?

I'm also wondering the same thing. Was there something about Yellow (the horse) from the book that was missing in the movie? I was totally expecting a "there's always money in the banana stand" type scenario. Anyone care to shed some light on this?

I read the book and don't recall any scenes about a horse, let alone a yellow horse. It may have been added to the film to emphasize that the two of them have a lot of stories that are shared even if one of them can't remember a particular story.

Other than that oddity, I thought the screenplay was an excellent representation of the Novel. I was wondering about condensing it into the time needed for a movie, but the narration moved the plot along.

“One never quite allows for the moron in our midst.” Agatha Christie, The Mirror Crack'd

So was I, particularly at the end when she goes back to the farm and sees the tractor with yellow markings!

In the book it was a cow named "Yellow #5", named that because of how they categorized the cattle on the farm.

It was merely a story about how Ben and his mother kept trying to castrate the cow but it kept getting away. Ben brings this up the first time he meets with Libby because something she says reminds him of the cow. She doesn't remember it. The whole point is to show how Ben wants Libby there to have conversations of the past to help him get through the day. Not sure why they changed it.

Yes "modern" film viewer - we know you were expecting something like that. Now go watch your Little jj abrams Fun Movies.

I figured that her mom sold one of the Yellow farm machines to raise the money to buy her youngest a horse. Hence: yellow.