The theater patron who suffers verbal abuse by Rachel's date was played by Peter Bonerz, who directed this episode. Bonerz is best known for starring on The Bob Newhart Show (1972).
At the end, when Joey's stage character says that he'll be back in 200 years to meet her great-great-great-granddaughter may have sounded like some kind of joke, but it wasn't. According to Einstein's Theory of Relativity, a spaceship traveling at near the speed of light could go on a trip of 200 years (to those on Earth), but to the space traveler only about four years would have passed for him.
The director's pretentious line to Joey and Kate ("a plague on both your houses!") originates from Shakespeare's "Romeo and Juliet."
Aside from the scene where Tommy screams at the chick and the duck across the hall, Phoebe is in Monica and Rachel's apartment for the whole episode.