On page 96 of the PDF version, the $ signs need to be escaped, in "an unconditional gift of $5 was twice as effective as a conditional offer of $50"). As it is now, the text between the $ signs is typeset in math mode.
(I post this here as I have no contact info for the PDF maintainer.)
Something cool on the PDF: the end of chapter 27. 503-504.
ETA: There is now a third thread, so send new comments there.
Since the first thread has exceeded 500 comments, it seems time for a new one, with Eliezer's just-posted Chapter 33 & 34 to kick things off.
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