At one point early in the novel, Lennie insists upon ketchup for his beans. After an angry outburst from George, Lennie completely backs off. I always find this moment to be quietly comical and sad as Lennie fails to manipulate George and gives up on his passion in the span of a minute or two.
In some ways Curley seems a ridiculous figure. Keeping a glove on that contains vaseline so his hand will be soft for his wife is ludicrous. George ridiculies Curley's virility after he warns Lennie not to look at his wife,
"Glove fulla vaseline," George said disgustedly. "An I bet he's eatin' raw eggs and writin' to the patent medicine houses."
Also, as mentioned in the previous post, Chapter One contains some little episodes of humorous descriptions. In Chapter Two, after Curley's wife departs, Lennie drools after her, and George treats him like he would a miscreant dog,
"Gosh, she was purty." He smiled admiringly. George looked quickly down at him and then he took him by and ear and shook him.
I don't think that you are not going to find many moments of comic interlude in the book. The scarcity of resources as well as the basic premise of migrancy in trying to establish dreams prevents any full embrace of comic interlude as a dominant form. Having said that, I actually think that in the first chapter, Lennie provides some brief moments of comic relief. When he imitates George putting his hands behind his head and relaxing on the ground, it is a moment of endearment. Additionally, when George gets angry at Lennie and Lennie counters with his desire to live in a cave, Steinbeck hints at the idea that Lennie knows how to manipulate the situation. In this light, there is some endearing comedy about the predicament. Another moments of comic relief is present at the time when Candy's dog is taken out to be shot. Such a horrific moment is punctuated with Whit talking about the fellow who used to work on the farm, but now had a story published in a magazine. The enthusiasm with which Whit reads the story, completely oblivious to the tension around him and the experiences of the others in the room, provides some moments of brevity in a very heavy situation.