Beam Me Up, Scotty! For reasons unknown, some people associate the phrase "ladies and germs" with this movie.
Defictionalization: There's a throwaway line about the "National Chicken Wing Festival" in Buffalo, New York. There was no such festival at the time the film was made, but now...
Executive Meddling: The movie was originally planned to be PG-13, but all swearing, a scene of Ozzy visiting sperm cells, and several more violent scenes were cut to be more kid friendly. This is considered by fans to be the worst decision made in production. Some have questioned on the movie would have been if it was PG-13. Some have believed that Warner Bros had trouble on deciding to market this as an animated comedy for adults or an animated kids' movie.
And once he takes over the office of mayor, he'll have many Happy Days.
What Could Have Been: In the original script and in early cuts of the movie, a scene was featured when Osmosis and Drix go to the Gonad's Gym. It involved them talking to the "exercising" sperm cells. The scene was cut in order to stay family friendly. The Gonad's Gym logo does appear on Drix's suitcase during a scene in police station locker room.
Also, the script reveals that Osmosis went to a family reunion when he was young. At that time Frank went to the doctors to have some blood removed, possibly in a blood drive. The needle drew out all of Ozzy's relatives, apparently leaving him all alone, which adds to his lone wolf status in the film. The ending has Frank getting a blood transfusion to save his life, with his own prior blood. And Ozzy's family returned to Frank, in a parody of the abductees returning in Close Encounters of the Third Kind. This was revealed in the DVD commentary.
One thing that was not cut out: a statue of a sperm with the inscription "OUR FOUNDER".
Will Smith said he was interested in the role of Osmosis, but schedule conflicts prevented that.