The Rule
Pick A Metaphor And Stick To It
First, it is like an anvil falling out of the sky and hitting him directly on the skull but then a scant view sentences later is "an atomic bomb going off in my brain."
And then it's multiple atomic bombs.
Metaphors are easy to abuse: Rather than telling someone what is happening and letting them experience it for themselves, the cheaper approach is to just tell them what the experience is like. It's even weaker and cheaper to simply switch from one metaphor to another, more intense metaphor, within a few sentences to describe the exact same thing.
Commentary
Cline's in a fix here: Similar to Trucks Carrying Goods and Workers, the "revelation" requires not truly imagining the life experience of someone who lived in the Oasis would be. He emphasizes something that would've been second nature to an inhabitant of his world by starting with a cartoon reference and going to an apocalyptic one.