When George comes up with the idea of using Laura to eavesdrop on his ex-girlfriend, Leifer's script had Jerry and George talking out of the sides of their mouths so Laura can't read their lips. Actors Jerry Seinfeld and Jason Alexander came up with the idea of using organic mouth-covering gestures on their own.
Monica Seles was approached to appear in the final scene where Kramer (Michael Richards) runs into her on the tennis court; she turned down the offer and a stuntwoman was used instead.
Marlee Matlin (Laura) can be seen on a poster in the lobby at NBC from the show Reasonable Doubts (1991).
Para-aminobenzoic acid, or PABA, was introduced in the 70s as a UVB filter in suntan lotion, but was later banned because of its tendency to cause allergic dermatitis and photosensitivity, and stain clothing.