Mad About You

Ursula Buffay (Lisa Kudrow), the waitress, is the twin sister of Phoebe Buffay (Lisa Kudrow) from Friends (1994). In one episode of Friends (1994), Fran (Leila Kenzle) and Jamie (Helen Hunt) visit the coffeehouse and mistake Phoebe for Ursula.

In Love Among the Tiles (1993), Paul and Jamie are trapped in their bathroom when the knob comes off the door. The bathroom has one small window. In Same Time Next Week (1994), Paul crawls easily out the window and stands on the fire escape.

As with any long-running show there are many inconsistencies between episodes. Characters' life histories, their birthdays and ages are reported differently from time-to-time as the writers invent new stuff for them that wasn't thought of when the series began.

Additional information from IMDb Guidelines for "Unacceptable Goofs"

• "Long running TV shows: As with any long-running show there are many inconsistencies between series. Characters' life histories, their birthdays and ages are reported differently from time to time as the writers invent new stuff for them that wasn't thought of when the series began."
• "Long running comedy shows: Almost all continuity errors between episodes of comedy shows will be rejected. Comedy series are driven by the need to be funny, and if it suits the writers' purpose to change details of a character's past for the sake of an entertaining plot line, then they're free to change it as much as they like as far as we're concerned."