In a deleted scene, it is explained how Newman (Wayne Knight) acquired the fleas. While doing his mail route, he had a run-in with a bulldog named Buford who was loaded with them. That's the same dog that Kramer (Michael Richards) unleashed on the mailman after he eats his last Mackinaw peach.
Mackinaw peaches are not real and were invented by the writers.
Christa Miller plays Paula. Not long after appearing in this episode, she auditioned for the The Drew Carey Show (1995). The producers weren't sure if Miller could do comedy, so she sent them a copy of this episode as evidence. It was a success and she got the job.
Elaine (Julia Louis-Dreyfus) finds candy wrappers in Jerry's (Jerry Seinfeld) couch while she's looking for the manuscript. Jerry realizes they must have belonged to Newman (Wayne Knight) when he was eating them in episode 6.2, The Big Salad (1994).
When Kramer (Michael Richards) comes out of Jerry's (Jerry Seinfeld) fumigated apartment, he mentions that he left a Mackinaw peach in the refrigerator. The manuscript, in all probability, has been left in the refrigerator by Kramer, as that is the only place Kramer mentions which Elaine (Julia Louis-Dreyfus) does not check. Also, Jerry asks for soda from Elaine. If she had opened the fridge to get the soda, she would have found the manuscript.