Title is misleading or missing.
Topic Number is missing or wrong.
Paper doesn't really address chosen topic, or misses much of the topic's requirements.
Organization of the paper is poor - things are discussed in widely separate sections. NOTE: outline, and dont be afraid to use a word processor to move things around.
Points you've already discussed are repeated.
Plagiarism - source material is copied with no or very little attempt to put into your own words. (You need to rephrase all material in your own words. You are allowed to quote, but only occasionally and not without attribution: explaining in your text who is being quoted and why they are a quotable source!)
Spelling and Grammar:
Overall proofreading was not done and needed to be. (Computer checkers are better than nothing, but will still miss a lot of mistakes.)
Apostrophes are not used on possessives. (Exception: possessive "its" gets no apostrophe; "it's" is a contraction meaning "it is.")
Apostrophes are used on common plurals (only very rare plurals get apostrophes).
Colons and semicolons are misused. (A colon sets something up, often a list; a semicolon breaks thing apart a bit more strongly than a comma.)
Verbs don't refer to their nouns (singular, plural) properly, or change tense for no reason.
Confusion amongst "there/ their/ they're," or "your/ you're," or "two/ to/ too."
Effect and affect are confused. (Effect is almost always a thing, affect is a verb.)
Proper usage is "try to do whatever," not "try and do it," as most people speak.
Footnotes are overused, or not used when needed, or formatted improperly. (See earlier section on footnotes.)
Quotations are overused (you're supposed to be paraphrasing, mostly, not copying) or are not attributed. Your reader should know who is talking, and why they are worth listening to!
In quotations, periods and commas are put outside the quotation marks. (Punctuation at the end of quotations go inside the quotation marks unless putting them there would change the meaning of the quotes.)
Style results in confusion or changes for no apparent reason.
Paper isn't long enough. (Text alone has to be at least 4 pages!)
Reference format is wrong, and/or information that's supposed to be there is missing.
Not enough references (should be at least 4 proper ones!).
You've footnoted a reference that's not on your reference list.
You've failed to include at least one recent reference.