Continuity mistake: In Chapter 19, Wade describes the small efficiency apartment he has moved into, which used to be an average hotel room. He says at one point that the room "was basically a cube, about ten meters long on each side." A ten-meter cube is actually a really big room - that's over 32 feet on each side, including ceiling height. Then, just to confirm that this is indeed a mistake, later in the same chapter he refers to "my tiny one-room apartment."
Character mistake: At the end of chapter 16, Wade describes Columbus, Ohio as looking like Oz at the end of the yellow brick road. However Oz is the name of the world. It was the emerald city that was at the end of the yellow brick road.
Continuity mistake: In Ch. 29 when the IOI eargear is first put on Wade, it is "clamped onto his right earlobe, piercing it in two locations." But then, in Ch. 31, Wade disengages the eargear and describes the pain as it "pulled free of the cartilage on my left ear." So there are two mistakes here: first, the eargear changes location from his right ear to his left, and second, it goes from being in his earlobe (which lacks cartilage) to a part of the ear that does contain cartilage.