Jerry Lewis was originally intended to appear as "Harold.'' Lewis' frequent collaborator, Bill Richmond, wrote the episode with the intention of Jerry Lewis appearing, but Lewis backed out of his commitment, and Bob Denver was cast instead.
"The President" (portrayed by an uncredited actor) is only seen briefly in two scenes near the end of the episode, first when he arrives at Tony's house for dinner, and then as he is leaving. He is only shown from behind, but in both scenes is wearing a cowboy hat, a trademark of Lyndon B. Johnson, who was President of the United States when this episode first aired. President Johnson was a great booster of the manned space program and had been instrumental in the creation of NASA.
Tony's full bathroom is shown, even his pink (!) laundry hamper - but no toilet. The same code of standards that prohibited showing of navels also, among other things, banned the image of a toilet on American television at the time. It wasn't until All in the Family (1971)(1971-79) that even the sound of a flushing toilet was heard, and that was considered groundbreaking at the time.
While Jerry Lewis was replaced by Bob Denver in the program, Barbara Eden had the pleasure of appearing with him on the March 19, 1968 broadcast of his popular NBC comedy-variety show, "The Jerry Lewis Show," on which she guest starred as a mountain maid in a country bumpkin comedy sketch with Lewis and co-star Merv Griffin besides showing off her vocals in a song-and-dance number of "Beautiful Things."
A possible reason for comedian Jerry Lewis demurring on appearing as the clumsy genie Harold was due to a scheduling conflict as he was in the midst developing and starring in a new weekly hour-long color comedy-variety series for NBC,The Jerry Lewis Show (1967), which premiered in September 1967 and aired after I Dream of Jeannie (1965) on Tuesday nights.