According to Richard Donner, the shoot on “Nightmare at 20,000 Feet” was, well, a nightmare. In order to make it look like a plane was up in the sky, the entire airplane set was hoisted high above the ground. Donner described the process thus:
“It was a tough shoot. It was an airplane … in a tank, elevated way off the ground. We had to climb up. We had massive wind machines. We had lightning machines. We had rain machines. We had effects machines working because we had to also turn the engines. There were no computers or anything to do it. Everything had to be live. Everything had to be synced.”
Because everything was so technically intense, and because the shoot had a very tight schedule, Donner said he like to keep the tone on the set light and relaxed. He felt that everyone would do a better job if they were content and jovial; being stressed out and overworked wasn’t a great way to make TV. Everyone was exhausted on the set of “Nightmare,” but everyone was having a good time. Donner himself, meanwhile, was mainlining coffee, trying to stay awake and just make it to the end.
It seems that the jovial set was perhaps a little too much leeway for Shatner and actor Edd Byrnes (from “77 Sunset Strip”), visiting the set that day to say hello to his wife, actress Asa Maynor (who played the episode’s flight attendant). It seems that there was an articulated dummy on set that was too tempting for Shatner and Byrnes not to do something with. When Donner was busy downing coffee, the two actors schemed.