They sometimes say comedy is harder to pull off than drama, and if that's the case, this episode shows a cast and crew at the top of their form. But what can I say about "The Trouble With Tribbles" that hasn't been said over and over? It's a classic, it's hilarious, it's got unforgettable scenes.
There is of course the great western-inspired bar brawl sequence that goes all out. And the scene where Kirk opens the door and thousands of tribbles fall down on him. And a light plot that knows better than to make any real threats. And classic confrontations with the Klingons, including a Klingon officer setting off Scotty by telling him the Enterprise is a garbage scow. But it's the cast interaction here that shows itself as really coming together. It occurred to me after again watching "The Trouble With Tribbles" that the natural chemistry evident in the original Trek cast is truly something special that hasn't been truly matched since.
Whether it's Kirk demanding "Who threw the first punch?" or the ending sequence where Kirk gets the runaround when trying to find out where all the tribbles went, the dialog and delivery is at top-notch sharpness. "Tribbles" is perhaps the best, most enjoyable comic piece the franchise has ever put out.