Who vs. whom (who is switched only with which)
Which vs. that
“Neither…nor” with subject-verb agreement using plural nouns (e.g. “Neither book nor the pencil is on the table” is tested; “Neither book nor the pencils are on the table” is not)
Among vs. between
Much vs. many
Fewer vs. less
Further vs. farther
Its vs. it’s
Their vs. they’re vs. there
Who’s vs. whose
May vs. might
A lot vs. alot
Pronoun case with comparisons (“She is a better soccer player than I” vs. “She is a better soccer player than me”)
Subject verb agreement with “none” (“None of us know vs. None of us knows”)
Colons (very, very occasionally, a correct answer will contain a colon, but they’re not explicitly tested)
Dashes
Apostrophes (plural vs. possessive)
And punctuation errors are virtually never tested on the Error-Identification section! Very rarely a comma splice will occur, but questions like that are rare exceptions.