Producer Gary Kurtz was having major financial difficulties while the production and filming on the film took place. He was in the middle of a divorce case which he lost and lost all of his profits from the Star Wars films in which were used to finance this film in part. This is one of the major reasons that the film has gone public domain since it's release.
Byron's line "I have slipped the surly bonds of Earth - put out my hand and touched the Face of God," is taken from the poem High Flight by John Gillespie Magee, Jr., a British-American aviator who died in a mid-air collision during WWII. On his grave is inscribed the first and last lines from his poem. This line is a direct allusion to that poem and befitting the film's predominant theme of aviation.
The part of Will Tasker was a notably different role for Hamill who had previously portrayed Luke Skywalker in "Star Wars" and was worried being typecast as the naive young hero in science fiction films.