In later years, William Shatner would claim that producers meddled with his portrayal of God for "political" reasons, preventing him from exploring the idea as he wanted. We love you, buddy, but we're pretty sure that wasn't the only issue with the movie. (Source)

Shatner would later apologize publicly for Star Trek V, though he blamed producers for not properly mentoring him as a first-time feature director. There might be some truth to that, but the main person we blame is whoever came up with Spock's rocket boots. Good grief. (Source)

George Takei (who plays Hikaru Sulu) and William Shatner have a long-standing beef, so Takei turned down the film when he found out his foe was directing. Takei eventually relented and found Shatner to be a "surprisingly pleasant" director, though he had some harsh words for the film's story. (Source)

The name Sha Ka Ree is the silliest inside joke of all time. Producers initially wanted Sean Connery for the role of Sybok, but when he was unable to sign on, they decided to honor him by making the object of Sybok's desire a near-homonym of his name. We use the word "honor" loosely, of course. (Source)