During the hiatus between seasons three and four, Larry Hagman got into a contract dispute with the producers and threatened to leave. If Hagman left the series, the plan was for the ambulance taking JR to the hospital to get into an accident and catch fire leaving JR burned and having plastic surgery to repair the damage and another actor would have taken over the role. The actor the producers had in mind to take over the role was Robert Culp.
Lucy's TR7 convertible from the previous season has been replaced with a silver Porsche 924.