How accurate is the quantum physics sequence?

Prompted by Mitchell Porter, I asked on Physics Stack­Ex­change about the ac­cu­racy of the physics in the Quan­tum Physics se­quence:

What er­rors would one learn from Eliezer Yud­kowsky’s in­tro­duc­tion to quan­tum physics?

Eliezer Yud­kowsky wrote an in­tro­duc­tion to quan­tum physics from a strictly re­al­ist stand­point. How­ever, he has no qual­ifi­ca­tions in the sub­ject and it is not his spe­cialty. Does it paint an ac­cu­rate pic­ture over­all? What mis­taken ideas about QM might some­one who read only this in­tro­duc­tion come away with?

I’ve had some in­ter­est­ing an­swers so far, in­clud­ing one from a friend that seems to point up a definite er­ror, though AFAICT not a very con­se­quen­tial one: in Con­figu­ra­tions and Am­pli­tude, a mul­ti­pli­ca­tion fac­tor of i is used for the mir­rors where −1 is cor­rect.

Physics Stack­Ex­change: What er­rors would one learn from Eliezer Yud­kowsky’s in­tro­duc­tion to quan­tum physics?