At first, Jack Nicholson seemed like a shoe-in for the job. Saul Zaentz had previously worked with the actor while producing “One Flew Over the Cuckoo’s Nest,” a box office smash-hit that won five Oscars, including an Academy Award for Best Picture. Considering just how well things worked out, why not team up with him again?
When it came time to cast Allie Fox for “The Mosquito Coast,” Nicholson immediately jumped out as a perfect fit, not least of all given his proven talent for playing unstable yet strangely charismatic characters. However, the success of “Cuckoo’s Nest” had also led to a power imbalance, at least in Zaentz’s mind. According to screenwriter Paul Schrader (via a 2021 article published by The Ringer):
“Jack was perfect for the character. And because Saul had made, or felt he had made Jack’s career with ‘Cuckoo’s Nest,’ he felt that Jack owed him one, and he lowballed Jack’s price. Jack said, ‘F*** you, Saul.’ And Saul said, ‘F*** you, Jack.’ Now, it was a perfect collaboration, but egos got involved, and that’s that.”
That being said, there were only so many actors who could play Allie Fox with enough nuance. With Nicholson out of the running, Ford was a good option. He didn’t come cheap though. Ironically, Schrader claimed Ford was paid roughly the same amount that Nicholson had requested. Schrader also made it bluntly clear which of the two actors he would’ve preferred for the film:
“[Zaentz] ended up paying Harrison Ford the same salary that Jack was asking. It got to be a pissing contest, and Jack did not want to be seen as an obligation. And obviously it would have been a much better film with Jack.”