Their scoring guide for Practice Test 1 is really not helpful for interpreting scores. It's on page 432 - for one thing, they seem to think the total number of questions in the Verbal sections is 56 and the total number of questions in the Quantitative sections is 52. ??? There's 40 questions total in each part.
Besides the weird scoring thing, I noticed several more errors, some of them really sort of bizarre, in the book over the last few days.
Firstly, on p. 157 (in the Vocabulary chapter), at the top of the page there is the word rent. The book then identifies this word as a verb and proceeds to give two definitions for it. Except that one definition indicates that it is an adjective ("torn (past tense of rend)") and the other indicates that it is a noun ("an opening or tear caused by such").
A couple more errors I've found in the book: on p. 388, in the solution for problem 14, it says, "1350 + 950 + 625 + 47, or 3,400." It should say, "1350 + 950 + 625 + 500, or 3,425" (as is obvious from the graph that the problem is based on). Also, on p. 394, in the solution for problem 4, the book gives the answer as B, but the explanation for the answer explains that the correct answer is A. (The explanation is correct.)
Secondly, on p. 425 (in Section 6: Verbal Reasoning of the first Practice Test), in the passage on which questions 7-10 are based, the last paragraph contains the sentence, "Using the inverse square law, scientists can then measure the how far [...]." That should probably just say "measure how far" (without the weird "the"). Also on that page, in answer choice D of question 7, the book says, "Knowledge of an object's brightness of an object [...]." That should probably say either "Knowledge of an object's brightness" or "Knowledge of the brightness of an object."
On p. 432 (in the section with the answers to the practice test, where it "explains" the scoring) the second sentence under both Verbal Reasoning and Quantitative Reasoning says, "Count of the number of questions [...]." That should probably say either "Count the number of questions" or "Count up the number of questions." The same error occurs again on p. 472, where the section with answers to the second practice test begins. Also, given that there are separate sections with the answers for each test, it seems odd that both p. 432 and p. 472 have boxes for you to score both tests.
On p. 436, at the very top of the page, in the answer for question 20, the book gives the answer as "6." This is correct, but it's inconsistent with their presentation of the answers and should probably say "C."
On p. 437, in the explanation for question 9, the book lists the correct answer as E (which it is, and which the explanation supports). Then in the last sentence of the explanation, they say "... which eliminates choice (E)." The answer choice that that sentence actually eliminates is choice D. Also on that page, in the explanation for question 11, an explanation is given, but no answer is put in bold. The explanation suggests that the answer should read, "An unsuspecting or naive buyer might fail to confirm [...]."
On p. 439, the explanation for question 20 makes no sense, as it is actually just a rephrase of the explanation for question 19. Question 20 isn't even a multiple choice question - it asks you to pick a sentence from the passage. (So I actually don't know that I got this question right, although I think I did and I counted it as correct when I calculated my score.)
On p. 444, the answer for question 16 is given as "B and E." This is correct, but once again it is inconsistent with their presentation of the answers and should probably say "cauterized and inured." Also on that page, the explanation for question 17 contains the phrase, "... which would reinforce that assumption that the manufacture is not getting kiwis from another country." The little grammar-nazi in my head is saying that this should really say "... which would reinforce the assumption that the manufacturer is not getting kiwis from another country." (The switch from that to the is probably debatable, but I'm pretty sure manufacture needs to be changed to manufacturer.)