For example, Audra Lindley was added to the cast (https://www.reddit.com/r/threescompany/comments/1uml9lz/audra_lindley_was_added_to_the_cast_of_a/) of a short-lived TV series Doc (https://en.wikipedia.org/wiki/Doc_(1975_TV_series)) at the start of the show's second season in September 1976. But Doc (https://jacksonupperco.com/2017/10/04/the-literary-club-read-an-original-doc-script/) however, was canceled soon after in October 1976. If Doc had been canceled in 1977, it would have been unlikely that Audra would have been on Three's Company. Keep in mind that Three's Company after-all, debuted (https://www.forbes.com/sites/marcberman1/2025/03/15/come-and-knock-on-their-door-threes-company-debuted-on-this-day-in-1977/) as a midseason replacement in March 1977.

Perhaps, the most obvious or consequential "butterfly effect" would be regarding Suzanne Somers' contract dispute during Season 5 (1980-81). If that particular incident never happens and Suzanne stays on Three's Company for the duration of its run, then Priscilla Barnes and Jenilee Harrison would've in all likelihood, have never had joined the show after Suzanne's abrupt departure.