Just as the Talosians have Capt. Pike re-enact his experiences on Rigel VII, there is the following situation: We (the TV viewers) are watching the court-martial (via TV) on the Enterprise; the court is watching the Talosians of 13 years before via their view-screen; and the Talosians are watching Capt. Pike relive his visit to Rigel VII via their view-screen.
When Number One and Yeoman J.M Colt transport to the planet, Vina states that Capt. Pike would be better reproducing with a computer than Number One. Majel Barrett provided the standard Federation computer voice throughout the various Star Trek series.
In the script, McCoy and Scott have a scene wherein they explain to Kirk how they figured out which computer bank Spock tampered with to lock the ship on course. They took perspiration readings on all banks, and since Spock's sweat has copper in it, traces of copper were found. This scene isn't seen in the episode.
This is the only episode of any Star Trek series which uses a captain's log to recap the events of the previous episode in a story arc. All others use a more traditional "previously, on..."-type of recap.
The Talosian "Keeper" alien was actually played by a woman - Meg Wyllie, as were all Talosians. The voice is alleged to have been dubbed by Malachi Throne, who portrays Commodore Jose Mendez. In order to differentiate the 'Talosians' voice from the Commodores, Throne's voice as the Talosian was slightly sped up.
"The Menagerie, Parts I" and "II" constitute the only two-parter in the run of Star Trek (1966). Combined, the two parts of this script only run to 64 pages, shorter than the scripts for many one-hour episodes. This is due to the heavy use of footage from Star Trek: The Cage (1986), which only had to be briefly noted by scene designations in the script format.
At the end of the episode, dramatic license is taken when Spock brings Pike to the transporter room. To make the scene as expedient as possible, Spock accompanies Pike to the transporter, sees him off and beams him down all in less than two seconds of screen time. However, it could be that the Keeper has merely created the illusion of Pike on the surface for Kirk's benefit, while awaiting the real Pike to be beamed down in a few minutes.
The footage the Talosians send to the Enterprise differs from what had happened in Star Trek: The Cage (1986) specifically, when Pike asks The Keeper if he'll give Vina back her illusion of beauty, The Keeper replies "And more" and restores Vina's appearance. However, in "The Cage", The Keeper not only restored Vina's beauty, but also created an illusion of Captain Pike for her and the two of them returned to the underground community. This was changed for "The Menagerie" so that The Keeper could show Captain Kirk the image of Pike restored to health (and back in his old-style Starfleet uniform) and going underground with Vina. However, the events of "The Cage" as originally depicted in the unaired pilot are still considered canonical and the footage transmissions as presented in "Menagerie" are assumed to have been edited by the Talosians. Therefore, when the real Pike finally joins Vina on Talos IV, it is possible that Vina does not notice the difference.