The plot: When the Joker parks a barge of laughing gas in downtown Gotham to cover a crime spree, Batman must race against the clock to stop him before Alfred, and half of the city, succumb to permanent insanity.
The Last Laugh may be my least favorite episode. It's certainly my least favorite episode featuring the Joker. Every other episode he's in is about something. In this one, he's just a criminal. A criminal who uses a terrorist attack to rob a city blind with the help of a murderous robot clown, but just a criminal. It could have been any villain in this episode, under scored by the fact that the Scarecrow also used a gas attack. Yes, he's attacking on April Fool's Day (wasn't it just Christmas? And why would you leave your home on any holiday in Gotham?), but it could have been the Scarecrow attacking on Halloween.
There's not much plot to speak of, or characterization. It's a good thing they set up Alfred as a surrogate father in the last episode because they certainly don't give Batman any reason to be extra concerned about Alfred's welfare in this one (other than good help is hard to find). Arguably, this is the episode that contrasts Batman's humorlessness with the Joker's mirthful attitude, but that doesn't ring as true in the episodes we've seen so far. The first thing we see Batman do, in fact, is smile and make a joke. So that kind of falls flat.
And the Joker is once again defeated when he trips and almost falls into a vat of chemicals. Sigh. At least we get to see him in his zoot suit this time.
I can see what they're trying to do. This episode, more than any other I can think of, resembles the old Max Fleisher Superman cartoons, which didn't have much plot or dialogue either. Just long chase sequences and action set pieces. The big difference between those shorts and this episode is that the Superman cartoons are seven minutes long. This episode tries to sustain a Tom and Jerry chase for twenty or so minutes. And fails.
I also don't like the score, for once. Yes, it's great that we hear the Joker's insane circus music theme for the first time, but it's overshadowed by the repeated funk drumbeat that plays throughout the episode. Shirley Walker uses a lot of different styles throughout the series, but for some reason this score just clashes with the symphonic style that usually characterizes the show.
There are a couple of good moments. Batman managing to punch the Joker through a periscope; the Joker's goons rolling their eyes as the boss makes yet another terrible joke, the reveal of what's under Captain Clown's mask (a shot that is straight out of the Fleisher cartoons).
We also get Efrem Zimbalist Jr.'s first take on Alfred, which unfortunately does not start out promisingly. We all know Alfred is an observational humorist, prop humor is beneath him.