The Danza: Almost all characters are credited in the style of "Laura Silverman as Laura". Arguably the characters also play themselves. H. Jon Benjamin as Benjamin Katz puts a little bit of a spin on it, where the actor's last name is the character's first name. Perhaps they didn't call him "Jon" since his father was already named Jonathan.
Marathon Running: Dr. Katz's sixth season contained 18 episodes; however, only six of them aired as planned before the series was cancelled. Comedy Central decided to air nine of the twelve unaired episodes in a 1999 Christmas Eve marathon, along with three reruns from the previous season, totalling six hours. However, the remaining three were initially unaired in the U.S. until 2002.
Short Run in Peru: The last three episodes, "Bakery Ben", "Uncle Nothing", and "Lerapy", didn't air in the U.S. until 2002, despite airing overseas before that.
Technology Marches On: In one episode, Dr. Katz tells Stanley and Julie a joke about a guy who was coming home early from a business trip, but catches his wife having sex with another man. The husband is devastated, and goes to see a shrink. After describing the problem, the therapist wonders, "Maybe she didn't get the fax." Nowadays, when such a message would likely be sent via cell phone or email, it's less likely that someone would send a fax saying they'll be home early.
Throw It In: As the show was improvised using a rough plot outline, this occurred in virtually every episode.
Unintentional Period Piece: Aside from Todd the video store clerk, computers are scarce: In an early episode, Dr. Katz announces to Laura that the office will be upgrading to a computerized filing system, but nothing ever seems to come of it. In another episode, Dr. Katz also mentions that he has a computer while talking to guest Marc Maron, but it's never shown on-screen.
In "The Particle Board", Marc Maron complains about how his friend is always trying to get him on the internet. This was in 1996. The whole idea of being reluctant to use the internet seems laughable today.