Unintentional Period Piece: Unavoidable, due to the monologue covering current event topics which can be head-scratching to younger viewers. This can even extend to the hosts themselves: In some shows during 1982, Johnny Carson complained about being in the news a lot lately. If you weren't alive at the time, he was referring to an incident where he was pulled over for drunk driving.
Steve Allen's version:
Missing Episode: Much of Steve Allen's tenure is gone, although the premiere seems to exist.
Allen: In case you're just joining us, this is Tonight, and I can't think of too much to tell you about it, but I want to give you the bad news first: this program is going to go on forever.note (Okay, so he was talking about the show's night-by-night length, but still...)
Jack Paar's version:
Writer Revolt: Jack walked off during the February 11, 1960 show after discovering that NBC censored a joke the previous night regarding a lady looking for the "water closet" who was directed to a wedding chapel due to her only using the initials "W.C." (the network cut into a news report over the joke). His sidekick, Hugh Downs, took over for the remainder of that telecast. Led to a Funny Moment when Parr returned a few weeks later with the words "...Now as I was saying..."