Thurston's The Geometry and Topology of Three-Manifolds was originally distributed as a typescript dated 1979. There is a $\mathrm{\TeX}$ version at https://web.archive.org/web/20230607095632/library.msri.org/books/gt3m/PDF/Thurston-gt3m.pdf, downloadable as a PDF and dated 2002. (Also available in the successor slmath.org website on a chapter by chapter basis, e.g. Chapter 3)
I've noticed that there are typos in the transcription and was wondering whether there is an official errata document. On the assumption that there isn't one yet, perhaps in the interim typos could be noted as answers to this question. (there seems to be a precedent for that on this site, e.g. Gauss Disq. Arithm. Translation Errata?).
Corrections are $\fbox{boxed}$
pg. iii: $\quad$ the discussion often tends to $\fbox{wander}$
pg. 113: $\quad$ In the proof of Lemma 5.10.1 each $\epsilon_{a/b}$ (where $a$ is 1 or 2 and $b$ varies) should instead be $\epsilon_a/b$ (e.g. $\epsilon_{2/2N}$ becomes $\epsilon_{2}/(2N)$).
pg. 154: $\quad$ $v = 12.04692 = \tfrac{1}{2}v(S^3 − D_8) > \boxed{v(C_3)}$