According to Edward Gross and Mark A. Altman’s “The Fifty Year Mission: The Complete, Uncensored, Unauthorized Oral History of ‘Star Trek:’ The First 25 Years,” the trouble started when the actors asked for a rehearsal table, which would enable them to contribute to the shaping of their characters. Director Joseph Pevney believes this was spurred on by Shatner, but it’s worth noting that he was not alone in suggesting rewrites. Leonard Nimoy, who played the Vulcan Science officer Spock, also had ideas about the show’s direction.
For Pevney, actors making contributions wasn’t the problem; it was the approach. As he told Gross and Altman, “Leonard could make his contributions in a quiet way by going into the office and talking to [producer Gene L.] Coon or [series creator Gene] Roddenberry, and they were all very receptive.” With Shatner, however, there was a significant shift in the on-set power dynamic. Per Pevney:
“So like a producer himself, Bill would arrange the table and seats and he would talk to the property man to move things over to the side. Well, when you’re doing television in five or six days, or whatever the schedule was back then, there’s no time for this constant rehearsal, a reading rehearsal, offstage, with pencils in hand and making changes. Because once you start making changes on the set, they have to be approved by the producer.”
This forced Roddenberry to issue a memo that diplomatically acknowledged the positive aspects of the actors’ script contributions while warning against too much interference. His missive ended thusly:
“[O]bviously none of us want this to become a habit since it is precisely this type of thing which has destroyed the format and continuity of more than one television series… where one person makes a change, others who may be less capable are encouraged to stick in their oar too, the director is encouraged to toss in some ideas of his.”