In a deleted scene, Kramer reveals that he fed Farfel turkish taffy, which would have explained the dog's erratic behavior and frequent barking.
The fictional film "Prognosis: Negative" is named after an unproduced screenplay by Larry David in which the main character wrongly assumes a negative prognosis is bad news. ("prognosis" means a likely outcome, while "diagnosis" means a collection of symptoms; therefore, a negative prognosis means a negative outcome, which is in fact bad news)
Farfel, the dog that never stops barking, wasn't played by an actual canine. Tom Williams, a voice-over artist, made all of Farfel's noises off-camera.
In this episode George (Jason Alexander) asks Jerry, "Isn't it more fun using the urinal?" In a previous episode however, he claimed to be a "stall man."