Here’s my list of things I noticed while reading through. (I removed the ones that were doubled with Jedavis’ list.) Not all of them are necessarily errors, some are just thoughts I had!
page 15: Cat, Saber-Tooth Tiger says “the other’s tusks are worth 4 gp each (18 gp total)”. There are 3 other tigers, so at 4 each, this should be 12 total.
page 21: Dog, Hunting has the value of a pup listed in copper pieces. Although the price is accurate, this seems odd (probably done to keep from having to include a decimal, but it seems like it might be confusing since I didn’t notice any other animal with a price listed in cp).
page 23: Dragon, Brown; while discussing how likely he is to be asleep, Kirashi is referred to as Kathus.
page 27: Dragon, White; Namazu’s meager hoard has two units of silver listed (200 sp and 750 sp).
page 35: Faravahar; When talking about turning undead, “earning a T result of a roll is normally required”, of should be if.
page 36: Faravahar; Phyladia has a 6th level spell slot, but no 6th level spells in her repertoire.
page 42: Storm Giant; The solitary storm giant doesn’t have a name, unlike most other important or interesting creatures (especially Lawful ones).
page 45: Gnome; In the Gnomish Arbalestier description, Explorer is typod (Exploer). I also note that Qyra’s AC of 10 is potentially confusing, since that’s her AC with shield, but she is more iconically using her arbalest.
page 45: Goblin; Xathrites’ spell repertoire lists magical missile instead of magic missile.
page 48: Grimlock; the grimlock witch doctor’s repertoire lists choking grasp instead of choking grip.
page 49-50: Hag: The hag lair description and mini stat blocks never explicitly mention that their caster level equals their HD. In addition, their repertoires all list 2nd in place of 5th (counting up 1, 2, 3, 4, 2).
page 56: Khepri; “may assume that weak or suppliant adventurers…” probably means ‘supplicant’.
page 63: Lizardman: Bottom paragraph starts “Sum’iddin has been experimenting with shamanic alchemy…” which would be terrifying if true! I think more likely though that Azriyaho, the tribe’s shaman, has been experimenting.
page 66: Lycanthrope, Werewolf; last paragraph says that they have five sacks of 5,000 SP totaling 30,000 SP. Either this should be six sacks, or only 25,000 SP.
page 72: Man, Pirate; in the description of Doukasi and Magosi, their class is listed as barnarian instead of barbarian.
page 75: Man, Mages; “The map leads to an ancient calender inlayed with jade”; inlayed should be inlaid.
page 89: Phase Tiger; is referred to as a displacer beast when talking about its pelt.
page 94: Sorcerous Sphere; last paragraph beginning “One of its tentacles” should be “On one of its tentacles”.
page 105: Wraith; the note about extra treasure refers to the current lair as the shadow lair.
page 107: Bottom of the page, “maximum load is adjusted by its STR modifier x (normal load/5).,” has an extra period in there.
page 111: First example, last sentence; “of the panther” should be “if the panther”.
page 112: “Baby monsters are two size categories small than” should be “smaller than”.
Notes on coloration in tables. I’m not sure if these are intentional or not (if it were me, it seems like something I’d do to remind myself to check these out again later), but I figured I’d mention them in case they were not.
page 122: The hyena’s trained value, adult value, child value, and baby value are in red.
page 124: The hag’s weight, size, and normal load are in red.
page 125: The Sea Serpent’s child value and baby value, along with the Skittering Maw’s baby value, are purple.
page 136: Last sentence, fourth paragraph: “This is why divine power why XP value…” has some extra sentence in there.
page 138: Bronze and iron golems can be used as a special component for +4 weapons; is this a typo or an intentional expansion for future mention? (ACKS Core only gives prices for +3 weapons, and doesn’t have an explicit formula for +X, although it does seem pretty easy to just say ‘take a +3 weapon and add 40k to the price’).
page 139: Storm Giant components list “lightning bold” instead of “lightning bolt”.
page 140: Greater Hell Hound spell listing seems to be missing a line break. Hippogriff spell listing “eyes of eagle” should be “eyes of the eagle”.
page 141: Dragon table, in the special abilities section, tail bone lists giant strength [tail bone] instead of listing which ability allows the tail bone to be usable for giant strength.
page 143: Flay Fiend seems to still have placeholder spells, with a description of which spells should go there instead of specific spells. (Personally, I like choking grip and uncanny gyration for them, because their movement method seems like a pretty uncanny gyrate to me.)
page 150: Man-Sized is listed twice, in the smallest and second-smallest size categories. I’m not actually sure if this is an error, but it’s confusing.
page 153: The text says that minor abilities are worth one-eighth a special ability, then says to divide them by 4 to calculate specials. The lamia example divides by 8. Then later, on page 163 during the double-headed eagle creation, it says that “but since two such abilities were rolled, they count as one *”. (Since flying and double attack are each two minor abilities, this is consistent with dividing by 4.)
page 155: Spellcasting; says the monster “my” cast spells instead of “may”.
page 183: Sixth paragraph (third from the bottom) refers to hero points instead of hit points.
page 189: Second paragraph, last sentence, “shores” has a space inside it.