Trivia: After Spock's funeral, the shot of the Enterprise coming toward the camera is a re-use of the shot after V'ger evolved at the end of The Motion Picture.
Trivia: Kriste Alley turned down the role of Savvik in star trek 3 & 4 for fear of being typecast.
Trivia: In 1983 this movie held the record for all-time best-selling home video release, largely owing to a then-bargain $39 price point. In the early 80s most movies on tape were priced around $70; the belief was that only enthusiasts and high-end customers were interested in owning movies and most people were satisfied renting. The stellar sales of Star Trek II proved there was a mass market for home video sales and the entire industry shifted in response.
Trivia: Early storyline development used essentially the setup for the Star Wars films only the villain was on the side of the rebellion. David was a (villainous, initially) version of Luke and it was a plot twist that Kirk is his father. The Genesis device was a planet-destroying weapon a la the Death Star, Khan lurked in the shadows dressed in a cloak and used psychic powers like the Emperor, and Spock would have died in the middle and at the end speak from beyond the grave like Obi Wan Kenobi.
Trivia: Khan says to Chekhov and Terrell, "I never forget a face," referring to Chekhov. But, Chekhov was not a member of the original cast of Star Trek at the time the Botany Bay was discovered in space, with no evidence Chekhov was meant to be in the crew already. So, Khan had never seen Chekhov's face for the first time until that moment on Star Trek II.
Chosen answer: According to the novelisation of the film the Genesis project was initially designed to be capable of creating an entire solar system. While the focus of the project eventually narrowed down to altering an individual planet, the sub-routines necessary to create a star were still in place and were activated when the device detonated within the nebula.
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