In Star Trek 3, the C-In-C said the Enterprise was "almost twenty years old".
But, if we add the original voyage of the Enterprise, under Robert April, which was 5 years, plus the time between "The Cage" and "The Menagerie", which was 13 years, plus the time between "Space Seed" and Star Trek 2 (which happens after "The Menagerie") which is 15 years we get 33 years.
Plus, the time between the intervals I mentioned (very little).
33 is more than 20.
How did Cartwright make such a serious mistake?
But, if we add the original voyage of the Enterprise, under Robert April, which was 5 years, plus the time between "The Cage" and "The Menagerie", which was 13 years, plus the time between "Space Seed" and Star Trek 2 (which happens after "The Menagerie") which is 15 years we get 33 years.
Plus, the time between the intervals I mentioned (very little).
33 is more than 20.
How did Cartwright make such a serious mistake?