First, a typo: in the acknowledgements (US version), in the list of beta readers there is a comma missing after callsign: Chaos (just before Darci Cole).
Second, some slightly weird phrasing: at the end of chapter 35, pg 350, there is this section:
What reads as off to me about this is that M-Bot's second guess of two mushrooms is him thinking of something that's better than "mushrooms". The thing is, the only thing in that situation/mindset/joke that would be not as good as two mushrooms - since two mushrooms is better than it - would be one mushroom. In other words, M-Bot first guesses an indeterminate amount of mushrooms, next specifically two, which would only be a step up as a present if his previous guess hadn't already been plural, and therefore equal to or greater than two.
My brain didn't catch on this until I'd read the book multiple times, and despite being logically weird, it's not something I can't imagine a person saying, since it's not like most people think and speak in perfect grammar, or put that much thought into random exchanges with friends. It's something that I noticed, and fixing it would be relatively easy (just change the first guess to "A mushroom?"). But I doubt it's something that will annoy most readers if you leave it be.